Silanetriol amino acids and uses thereof

Abstract

The present invention relates to an amino acid comprising a silanetriol (-Si(OH)3) functional group, as well as polypeptides comprising an amino acid comprising a silanetriol (-Si(OH)3) functional group. Moreover, the present invention relates to methods of obtaining amino acids comprising silanetriol (-Si(OH)3) functional groups and methods of immobilizing polypeptides comprising silanetriol (-Si(OH)3) functional groups on a solid.

Description

[0001] New PCT-Patent Application Based on EP 23315348.5 Scientist of Fortune S.A. Vossius Ref.: AG2918 PCT BS SILANETRIOL AMINO ACIDS AND USES THEREOF BACKGROUND OF THE INVENTION The chemical constitution common to all known living cells is apparently restricted to the ten elements C, H, N, O, P, S, K, Mg, Zn and Mn. Certain elements are present in the composition of most species but absent in others, thus Escherichia coli is devoid of Na and Cl, Saccharomyces cerevisiae of Mo and Lactobacillus plantarum of Fe. The templated biosynthesis of informational polymers proceeds by exclusively incorporating the C, H, N, O, P subset in nucleic acids (as catalyzed by RNA and DNA polymerases) and the C, H, N, O, S subset in proteins (as catalyzed by ribosomes). The only known exception to the restricted specification of informational bioelements is selenium, the incorporation of which occurs in some proteins of certain species. Elucidation of the enzymatic machinery that underlies the biosynthesis and coding of selenocysteinyl-tRNA, thereby endowing proteins with the selenol catalytic group, represented a major advance in biochemical and evolutionary understanding. Taking selenocysteine as a model, the inventors set out to experimentally add silicon to the list of informational bioelements and more specifically to evolve descendants of common microbial species that would employ the silanetriol group as an additional amino acid side chain in their genetic code. The silanetriol group (pKa=10) indeed formally corresponds to the substitution of carbon by silicon in the carboxyl group (pKa=4), which attenuates its acidic character and allows its spontaneous self-condensation into siloxanes, notably silsequioxanes (Figure 1). A few recent experimental advances are relevant for the goal of introducing silanetriol in proteins. The catalytic mechanisms of silicic acid (Si(OH)4) polymerization by the enzymes silaffin from diatoms and silicatein from sponges have been precisely characterized (Acta Biomateriala 2021, 120, 38-56). These enzymes are able to connect Si-O bonds without containing silicon in their own structures. Very significantly, variants of heme proteins were engineered by the Arnold group to catalyze the formation of Si-C bonds, thereby accomplishing a tour de force for the reason that such bonds do not appear in the structure of any known molecule synthesized by a living organism (Science, 2016, 354, 1048–1051 and ACS Cent. Sci. 2021, 7, 944–953). Using orthogonal tRNA / synthetase systems, two silicon- containing amino acids were incorporated into bacterial proteins as NMR probes, namely 4- trimethylsilyl-phenylalanine ex vivo (J. Biomol. NMR 2018, 71, 287–293) and N6-trimethylsilyl- methoxycarbonyl-lysine in vivo (J. Am. Chem. Soc.2021, 143, 1133–1143). Silicon is in this case bonded to carbon by its four valences, leaving the biological mobilization of silanetriol in terra incognita. The incorporation of silicon into amino acid and peptide analogs has mainly been studied for medicinal purposes thus far (Chem. Soc. Rev.2009, 38, 1002–1010 and Chem. Rev.2016, 116, 11654–11684). Most were derived from commercial alkylsilyl or arylsilyl precursors and handily prepared because of their imperviousness to water. Few examples of amino acids were reported in which silicon is bonded to oxygen atoms, namely alanine (Helvetica Chimica Acta 2004, 87, 1681–1696; Organometallics 2005, 24, 1780–1783; and Eur. J. Org. Chem.2015, 2015, 3352–3360) and phenylalanine (Peptide Science 2018, 110, e24069) dimethylsilanols. Silanediols were pioneered in 1998 by Sieburth as isosteric analogs of the tetrahedral intermediate in peptide bond hydrolysis (Angew. Chem. Int. Ed. Engl. 1998, 37, 812–814). Various proteolytic enzyme inhibitors were discovered following this approach (angiotensin converting enzyme (J. Am. Chem. Soc.2002, 124, 7363–7375), HIV protease (Chem. Biol.2001, 8, 1161–1166), and thermolysin (J. Org. Chem.2004, 69, 3008–3014)) as well as a zinc-binding inhibitor of histone deacetylases (ChemMedChem 2014, 9, 614–626). In the same vein, Enghild and Skrydstrup developed a family of inhibitors of the human neutrophil esterase, a serine protease enzyme (J. Med. Chem. 2012, 55, 7900–7908). The Sieburth's group also prepared an amino acid bearing a distal silanediol, 6-dihydroxymethylsilyl-L-norleucine, through alkene hydrosilylation and showed that it undergoes acid-dependent siloxane oligomerization (J. Org. Chem.2012, 77, 2901–2906). Compared to silanols and silanediols, silanetriols form an exotic class of compounds whose synthetic access remains more arduous (Coord. Chem. Rev. 2016, 323, 87–106). They have mainly been synthesized as precursors of hybrid materials (J. Mater. Chem.2003, 13, 2885– 2889). Their structures based on a geminal tri-hydroxy group mimic the transition state of ester hydrolysis and, indeed, some simple alkyl and aryl silanetriols were found inhibitory to acetylcholine esterase (Bioorg. Med. Chem. Lett.2011, 21, 363–365), validating the potential of these silicon derivatives to interfere with biomolecules. Despite these advances, there is a need in the art for amino acids comprising a silanetriol function, thereby allowing the introduction of the silanetriol function into polypeptides or proteins, or into the cellular metabolism. For example, one objective of the present invention is to endow living cells with the self-condensation of silanetriol into siloxane Si-O clusters and explore new types of protein architectures, by introducing non-redox alternatives to disulfide crosslinks and Fe-S clusters. Furthermore, amino acids comprising a silanetriol function may be used to ensure the containment of microbial strains requiring a silanetriol amino acid as nutrient. Since no metabolic reaction is known to form Si-C bonds, silanetriol-dependent cells escaping from a laboratory would be unlikely to acquire a biosynthetic pathway, bypass their nutritional need and disseminate in the wild. Accordingly, the objective technical problem underlying the present invention can be seen as the provision of amino acids capable of conferring new functionalities to polypeptides and / or organisms. SUMMARY OF THE INVENTION The present invention is characterized in the herein provided embodiments and claims. In particular, the present invention relates, inter alia, to the following embodiments: 1. An amino acid comprising a silanetriol (-Si(OH)3) functional group. 2. The amino acid according to embodiment 1, wherein the amino acid is according to formula (I): or its salt, wherein: Z is C0-6 alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4 alkyl)-, -CO-, -CONH-, -NHCO-, -CON(C1- 4 alkyl)-, -N(C1-4 alkyl)CO-, -Si(OH)2, -Si(CH3)2-, -SiF2-, -SO2-, or -PO2H-, and / or one or more hydrogen atoms can be independently replaced by C1-4alkyl, -OH, -O(C1-4alkyl), -SH, - S(C1-4 alkyl), -NH2, -NH(C1-4 alkyl), or -N(C1-4 alkyl)(C1-4 alkyl); and X and Y are each independently hydrogen, halogen, -CN, C1-4alkyl, -OH, -O(C1-4alkyl), - (C1-4alkylene)-OH, -SH, -S(C1-4alkyl), -(C1-4alkylene)-SH, -NH2, -NH(C1-4alkyl) or -N(C1-4alkyl)(C1-4alkyl), -COOH, -CONH2, -CONH(C1-4alkyl), -CON(C1-4alkyl)(C1-4alkyl), -SO3H or -PO3H2. 3. The amino acid according to embodiment 2, wherein Z is C0-6alkylene, and / or X and Y are each independently hydrogen, -CN, C1-4alkyl, -OH, -O(C1-4alkyl), -(C1-4alkylene)-OH, -SH, -S(C1-4alkyl), -(C1-4alkylene)-SH, -NH2, -NH(C1-4alkyl) or -N(C1-4alkyl)(C1-4alkyl). 4. The amino acid according to embodiment 2 or 3, wherein the amino acid is according to formula (Ia): , wherein n is an integer ranging from 1 to 7, preferably from 1 to 5, more preferably from 1 to 3, or its salt, preferably wherein the amino acid of formula (Ia) is an amino acid of formula (Ib): or its salt. 5. A polypeptide comprising the amino acid according to any one of embodiments 1 to 4. 6. The polypeptide according to embodiment 5, wherein the polypeptide is immobilized on a solid by means of a siloxane bond. 7. The polypeptide according to embodiment 6, wherein the solid is a surface or a particle. 8. The polypeptide according to embodiment 6 or 7, wherein the solid comprises a functional group that allows for the formation of the siloxane bond. 9. The polypeptide according to embodiment 8, wherein the functional group that allows for the formation of the siloxane bond is comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, or a phosphate salt of phosphoric acid. 10. The polypeptide according to any one of embodiments 6 to 9, wherein the solid comprises or consists of glass, concrete, ceramics, zeolites, and / or clays. 11. The polypeptide according to any one of embodiments 5 to 10, wherein the polypeptide is an enzyme. 12. The polypeptide according to any one of embodiments 5 to 11, wherein the polypeptide is displayed on the surface of a cell, in particular a microbial cell. 13. The polypeptide according to any one of embodiments 5 to 10, wherein the polypeptide is comprised in a virus particle, in particular in the capsid of a virus particle. 14. A siloxane (Si-O) cluster comprising the amino acid according to any one of embodiments 1 to 4 and / or the polypeptide according to any one of embodiments 5 to 13. 15. The siloxane (Si-O) cluster according to embodiment 14, wherein the siloxane cluster comprises at least one siloxane bond, in particular wherein the siloxane bond comprises the structure (Si-O-Si), (Si-O-B) or (Si-O-P). 16. A solid surface or particle covalently linked to the amino acid according to any one of embodiments 1 to 4 or the polypeptide according to any one of embodiments 5 to 13, wherein the amino acid or the polypeptide is covalently linked to the surface or the particle via a siloxane bond, in particular wherein the siloxane bond comprises the structure (Si-O-Si), (Si-O-B) or (Si-O-P). 17. The solid surface or particle according to embodiment 16, wherein the surface or particle comprises a molecule selected from the group consisting of: a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, and a phosphate salt of phosphoric acid. 18. The solid surface or particle according to embodiment 16 or 17, wherein the surface or particle comprises or consists of glass, concrete, ceramics, zeolites, and / or clays. 19. An aminoacylated tRNA comprising the amino acid according to any one of embodiments 1 to 4. 20. A method for obtaining an amino acid of embodiment 4, wherein n is an integer ranging from 2 to 7, the method comprising the step of reacting the compound of formula (II): (II) with HSi(OR)3in the presence of a Karstedt catalyst, wherein PG1and PG2are protecting groups for -NH2and -COOH groups, respectively, and each R is independently of each other selected from C1-6alkyl. wherein the method further comprises the step(s) of deprotecting -Si(OH)3, -NH2and - COOH groups in the obtained product. 21. The method of embodiment 20, wherein PG1is Cbz group, PG2is C1-6alkyl, and / or each R is ethyl. 22. A method for obtaining an amino acid of any one of embodiments 2 to 4, the method comprising the step of reacting LG-Z-CXY-Si(OR)3, with PGN-CH2-COO-PG2 pretreated with a base capable of generating PGN-CH--COO-PG2 carbanion, wherein Z, X and Y are as defined in embodiment 2 or 3, LG is a leaving group, PGN is a protected -NH2 group, PG2 is a protecting group for -COOH group, and each R is independently of each other selected from C1-6 alkyl and C2-6 alkenyl, wherein the method further comprises the step(s) of deprotecting Si(OH)3, -NH2 and - COOH groups in the obtained product. 23. The method of embodiment 22, wherein n is 1, LG is iodo, PGN is (phenyl)2C=N-, PG2 is C1-6 alkyl, and / or each R is allyl. A method of producing a polypeptide comprising a silanetriol amino acid at a specified position in a cell, the method comprising: a) growing, in an appropriate medium, the cell, wherein the cell comprises a nucleic acid that encodes the polypeptide, and wherein the nucleic acid comprises at least one selector codon; and b) providing the amino acid according to any one of embodiments 1 to 4; wherein the cell further comprises: c) a nucleic acid sequence encoding an orthogonal aminoacyl-tRNA synthetase (O-RS), and, d) an orthogonal tRNA (O-tRNA), that recognizes the selector codon, wherein said O—RS aminoacylates the O-tRNA with the amino acid according to any one of embodiments 1 to 4. The method according to embodiment 24, wherein the selector codon is a nonsense codon, in particular an amber stop codon. A method of immobilizing a polypeptide on a solid, the method comprising the steps of: a) providing a solid comprising a functional group that allows for the formation of a siloxane bond; b) contacting the solid of step (a) with the polypeptide according to any one of embodiments 5 to 13; c) immobilizing the polypeptide on the solid. A method of equipping a solid with a biological agent, the method comprising the steps of: a) providing a solid comprising a functional group that allows for the formation of a siloxane bond; b) equipping the solid with a biological agent by contacting the solid of step (a) with the amino acid according to any one of embodiments 1 to 4 or the polypeptide according to any one of embodiments 5 to 13. 28. The method according to embodiment 26 or 27, wherein the solid is a surface or a particle. 29. The method according to any one of embodiments 26 to 28, wherein the functional group that allows for the formation of a siloxane bond is comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, or a phosphate salt of phosphoric acid. 30. The method according to any one of embodiments 26 to 29, wherein the solid comprises or consists of glass, concrete, ceramics, zeolites, and / or clays. That is, the present invention is based on the surprising finding that the silanetriol functional group can be incorporated into amino acids. The findings reported herein bode well for the future biodiversification of silicon and the incorporation of silanetriol as an additional functionality of proteins in vivo. It is further demonstrated that silanetriol amino acids serve as nitrogen sources for bacteria expressing appropriate aminotransferases. The transamination products, silanetriol oxo acids, will likely give rise to aldehydes and acyl-CoA thioesters through the action of thiamine enzymes and in turn generate an unprecedented cascade of secondary metabolites. A swell of metabolic innovation is to be expected from the synthetic availability of silanetriol amino acids and their propensity to undergo the enzymatic conversions of canonical amino acids. Moreover, it was surprisingly found that silanetriol amino acid according to the invention can be linked to suitable molecules or materials via siloxane bonds, preferably when incorporated in a peptide or protein. This has various potential applications ranging from the immobilization of polypeptides, viral particles or cells on solid surfaces or the functionalization of otherwise inert materials, including inert mineral materials. DETAILED DESCRIPTION OF THE INVENTION As mentioned before, the present invention relates, in one embodiment, to an amino acid comprising a silanetriol functional group. It will be understood that salt forms of said amino acid are also encompassed by the present invention. As further understood herein, a silanetriol functional group is a group according to formula -Si(OH)3. The term “amino acid”, as understood herein, refers to a compound comprising at least one - COOH group and one -NH2group (or their ionized forms, in particular wherein -COO- group and -NH3- are present at the same time in one molecule, which can be also referred to as zwitterionic form). The amino acid, as referred to herein, may be an -amino acid, that is, a compound comprising a moiety according to formula: H2N COOH . It is further preferred that -amino acid includes a moiety according to formula:H2N COOH . It is to be understood that the configuration of the stereogenic center corresponds to that seen in 20 standard proteinogenic -amino acids (i.e., Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val). However, -amino acid with an inverted configuration at their stereogenic center, in other words -amino acid that comprise a moiety according to formula: H2N COOH , are also encompassed by the present invention. The term amino acid may also encompass -amino acids, -amino acids and / or -amino acids. Preferably, the amino acid is an -amino acid, as referred to herein, preferably comprising a moiety according to formula term “amino acid” may also refer to a monovalent or divalent radical derived from an “amino acid” as described herein above, wherein preferably an amino group and / or a carboxylic acid group may serve as point(s) of attachment, preferably through an amide bond. Thus, the term “amino acid” may refer to an amino acyl moiety attached to the rest of the molecule, e.g., through a -CO- group formed from its carboxylic acid group, and / or through a -NH- group formed from its amino group. Thus, accordingly, it is preferred that the amino acid of the present invention comprises a silanetriol (-Si(OH)3) functional group and a moiety according to formulaH2N COOH , which preferably is a moiety according to formulaH2N COOH . Preferably, the amino acid of the present invention is an amino acid (or, more generally speaking, a compound) according to formula (I): or its salt. In formula (I), Z is C0-6alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4alkyl)-, -CO-, -CONH-, -NHCO-, -CON(C1-4alkyl)-, -N(C1-4alkyl)CO-, -Si(OH)2-, -Si(CH3)2-, -SiF2-, -SO2-, or -PO2H- and / or one or more hydrogen atoms can be independently replaced by C1-4alkyl, -OH, -O(C1-4alkyl), -SH, -S(C1-4alkyl), -NH2, -NH(C1-4alkyl), -N(C1-4alkyl)(C1-4alkyl). Preferably, Z is C0-6alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4alkyl)-, -CO-, -CONH-, -NHCO-, -CON(C1-4alkyl)-, -N(C1-4alkyl)CO-, -Si(OH)2-, -Si(CH3)2-, or -SiF2- and / or one or more hydrogen atoms can be independently replaced by C1-4alkyl, -OH, -O(C1-4alkyl), -SH, -S(C1-4alkyl), -NH2, -NH(C1-4alkyl), -N(C1-4alkyl)(C1-4alkyl), preferably by C1-4alkyl, -OH, -SH, and -NH2, more preferably by C1-4 alkyl, or -OH. More preferably, Z is C0-6alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4 alkyl)-, -CONH-, -NHCO-, - CON(C1-4alkyl)-, or -N(C1-4alkyl)CO-, and / or one or more hydrogen atoms can be independently replaced by C1-4 alkyl, -OH, -O(C1-4 alkyl), -SH, -S(C1-4 alkyl), -NH2, -NH(C1-4 alkyl), -N(C1-4 alkyl)(C1-4 alkyl), preferably by C1-4 alkyl, -OH, -SH, and -NH2, more preferably by C1-4 alkyl, or -OH. Even more preferably, Z is C0-6alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4alkyl)-, -CONH-, or -NHCO-, and / or one or more hydrogen atoms can be independently replaced by C1-4 alkyl, -OH, -O(C1-4 alkyl), -SH, -S(C1-4alkyl), -NH2, -NH(C1-4alkyl), -N(C1-4alkyl)(C1-4alkyl), preferably by C1-4alkyl, - OH, -SH, and -NH2, more preferably by C1-4alkyl, or -OH. Still more preferably, Z is C0-6alkylene, wherein one or more, preferably non-adjacent, -CH2- groups can be independently replaced by -O-, -S-, -NH-, -N(C1-4 alkyl)-, or -CONH-, and / or one or more hydrogen atoms can be independently replaced by C1-4 alkyl, -OH, -O(C1-4 alkyl), -SH, -S(C1-4 alkyl), -NH2, -NH(C1-4 alkyl), -N(C1-4 alkyl)(C1-4 alkyl), preferably by C1-4 alkyl, -OH, -SH, and -NH2, more preferably by C1-4 alkyl, or -OH. Again more preferably, Z is C0-6 alkylene, wherein one or more hydrogen atoms can be independently replaced by C1-4 alkyl, -OH, -O(C1-4 alkyl), -SH, -S(C1-4 alkyl), -NH2, -NH(C1-4 alkyl), -N(C1-4 alkyl)(C1-4 alkyl), preferably by C1-4 alkyl, -OH, -SH, and -NH2, more preferably by C1-4 alkyl, or -OH. Most preferably, Z is C0-6 alkylene. Preferably, said alkylene is a linear alkylene. Particularly suitable Z are methylene (-CH2-), ethylene (in particular -CH2CH2-) and propylene (in particular -CH2CH2CH2-). In formula (I), X and Y are each independently hydrogen, halogen, -CN, C1-4 alkyl, -OH, -O(C1-4 alkyl), -(C1-4 alkylene)-OH, -SH, -S(C1-4 alkyl), -(C1-4 alkylene)-SH, -NH2, -NH(C1-4 alkyl) or -N(C1-4 alkyl)(C1-4 alkyl), -COOH, -CONH2, -CONH(C1-4 alkyl), -CON(C1-4 alkyl)(C1-4 alkyl), -SO3H or - PO3H2. Preferably, X and Y are each independently hydrogen, halogen, -CN, C1-4 alkyl, -OH, -O(C1-4 alkyl), -(C1-4alkylene)-OH, -SH, -S(C1-4alkyl), -(C1-4alkylene)-SH, -NH2, -NH(C1-4alkyl) or -N(C1-4alkyl)(C1-4alkyl), -COOH, -CONH2, -CONH(C1-4alkyl), or -CON(C1-4alkyl)(C1-4alkyl). More preferably, X and Y are each independently hydrogen, -CN, C1-4alkyl, -OH, -O(C1-4alkyl), -(C1-4alkylene)-OH, -SH, -S(C1-4alkyl), -(C1-4alkylene)-SH, -NH2, -NH(C1-4alkyl) or -N(C1-4alkyl)(C1-4alkyl). Even more preferably, X and Y are each independently hydrogen, halogen, -CN, -OH, -SH, or - NH2, wherein it is preferred that at least one of X and Y is hydrogen, unless X and Y are both - F. Still more preferably, X and Y are both hydrogen or both F, whereas it is particularly preferred that X and Y are both hydrogen. Accordingly, the amino acid of formula (I) may be an amino acid according to formula (Ia): , or its salt. In formula (Ia), n is an integer ranging from 1 to 7. Thus, n can be 1, 2, 3, 4, 5, 6 or 7. Preferably, n is an integer ranging from 1 to 5. Even more preferably, n is an integer ranging from 1 to 3. Accordingly, n may be 1 and –(CH2)n– as defined in formula (Ia) is -CH2-. Alternatively, n may be 2, and –(CH2)n– as defined in formula (Ia) is -CH2CH2-or -CH(CH3)-. Alternatively, n may be 3, and –(CH2)n– as defined in formula (Ia) is -CH2CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or - CH(CH2CH3)-. Thus, preferably, –(CH2)n– is -CH2-, -CH2CH2- or -CH2CH2CH2-. Preferably, the amino acid of formula (Ia) is an amino acid of formula (Ib): or its salt. It is to be understood that n and –(CH2)n– in formula (Ib) are as defined for formula (Ia). Particularly preferred compounds of formula (Ib) are the following compounds, or their salts: It is to be understood that the scope of the invention embraces all salts, including pharmaceutically acceptable salt forms of the amino acids of the present invention, in particular of the compounds of formula (I), which may be formed, e.g., by protonation of an atom carrying an electron lone pair which is susceptible to protonation, such as an amino group, with an inorganic or organic acid, or as a salt of an acid group (such as a carboxylic acid group) with a physiologically acceptable cation. Exemplary base addition salts comprise, for example: alkali metal salts such as sodium or potassium salts; alkaline earth metal salts such as calcium or magnesium salts; zinc salts; ammonium salts; aliphatic amine salts such as trimethylamine, triethylamine, dicyclohexylamine, ethanolamine, diethanolamine, triethanolamine, procaine salts, meglumine salts, ethylenediamine salts, or choline salts; aralkyl amine salts such as N,N-dibenzylethylenediamine salts, benzathine salts, benethamine salts; heterocyclic aromatic amine salts such as pyridine salts, picoline salts, quinoline salts or isoquinoline salts; quaternary ammonium salts such as tetramethylammonium salts, tetraethylammonium salts, benzyltrimethylammonium salts, benzyltriethylammonium salts, benzyltributylammonium salts, methyltrioctylammonium salts or tetrabutylammonium salts; and basic amino acid salts such as arginine salts, lysine salts, or histidine salts. Exemplary acid addition salts comprise, for example: mineral acid salts such as hydrochloride, hydrobromide, hydroiodide, sulfate salts (such as, e.g., sulfate or hydrogensulfate salts), nitrate salts, phosphate salts (such as, e.g., phosphate, hydrogenphosphate, or dihydrogenphosphate salts), carbonate salts, hydrogencarbonate salts, perchlorate salts, borate salts, or thiocyanate salts; organic acid salts such as acetate, propionate, butyrate, pentanoate, hexanoate, heptanoate, octanoate, cyclopentanepropionate, decanoate, undecanoate, oleate, stearate, lactate, maleate, oxalate, fumarate, tartrate, malate, citrate, succinate, adipate, gluconate, glycolate, nicotinate, benzoate, salicylate, ascorbate, pamoate (embonate), camphorate, glucoheptanoate, or pivalate salts; sulfonate salts such as methanesulfonate (mesylate), ethanesulfonate (esylate), 2-hydroxyethanesulfonate (isethionate), benzenesulfonate (besylate), p-toluenesulfonate (tosylate), 2-naphthalenesulfonate (napsylate), 3-phenylsulfonate, or camphorsulfonate salts; glycerophosphate salts; and acidic amino acid salts such as aspartate or glutamate salts. Preferred salts of the amino acids of the present invention or the compounds of formula (I) include a hydrochloride salt, a hydrobromide salt, a mesylate salt, a sulfate salt, a tartrate salt, a fumarate salt, an acetate salt, a citrate salt, and a phosphate salt. A particularly preferred salt of the amino acids of the present invention or the compound of formula (I) is a hydrochloride salt. The present invention also specifically relates to the amino acid of the present invention or the compound of formula (I), including any one of the specific compounds of formula (I) described herein, in non-salt form or in a zwitterionic form. Moreover, the scope of the invention embraces the amino acids of the present invention or the compounds of formula (I) in any solvated form, including, e.g., solvates with water (i.e., as a hydrate) or solvates with organic solvents such as, e.g., methanol, ethanol, isopropanol, acetic acid, ethyl acetate, ethanolamine, DMSO, or acetonitrile. All physical forms, including any amorphous or crystalline forms (i.e., polymorphs), of the amino acids of the present invention or the compounds of formula (I) are also encompassed within the scope of the invention. It is to be understood that such solvates and physical forms of salts of the amino acids of the present invention or the compounds of the formula (I) are likewise embraced by the invention. Furthermore, the amino acids of the present invention or the compounds of formula (I) may exist in the form of different isomers, in particular stereoisomers (including, e.g., geometric isomers (or cis / trans isomers), enantiomers and diastereomers) or tautomers (including, in particular, prototropic tautomers, such as keto / enol tautomers or thione / thiol tautomers). All such isomers of the amino acids of the present invention or the compounds of formula (I) are contemplated as being part of the present invention, either in admixture or in pure or substantially pure form. As for stereoisomers, the invention embraces the isolated optical isomers of the amino acids or the compounds according to the invention as well as any mixtures thereof (including, in particular, racemic mixtures / racemates and non-racemic mixtures). The racemates can be resolved by physical methods, such as, e.g., fractional crystallization, separation or crystallization of diastereomeric derivatives, or separation by chiral column chromatography. The individual optical isomers can also be obtained from the racemates via salt formation with an optically active acid followed by crystallization. The present invention further encompasses any tautomers of the amino acids of the present invention or the compounds of formula (I). It will be understood that some compounds may exhibit tautomerism. In such cases, the formulae provided herein expressly depict only one of the possible tautomeric forms. The formulae and chemical names as provided herein are intended to encompass any tautomeric form of the corresponding compound and not to be limited merely to the specific tautomeric form depicted by the drawing or identified by the name of the compound. The scope of the invention also embraces amino acids of the present invention or compounds of formula (I), in which one or more atoms are replaced by a specific isotope of the corresponding atom. For example, the invention encompasses amino acids of the present invention or compounds of formula (I), in which one or more hydrogen atoms (or, e.g., all hydrogen atoms) are replaced by deuterium atoms (i.e.,2H; also referred to as “D”). Accordingly, the invention also embraces amino acids of the present invention or compounds of formula (I) which are enriched in deuterium. Naturally occurring hydrogen is an isotopic mixture comprising about 99.98 mol-% hydrogen-1 (1H) and about 0.0156 mol-% deuterium (2H or D). The content of deuterium in one or more hydrogen positions in amino acids of the present invention or compounds of formula (I) can be increased using deuteration techniques known in the art. For example, a compound of formula (I) or a reactant or precursor to be used in the synthesis of the compound of formula (I) can be subjected to an H / D exchange reaction using, e.g., heavy water (D2O). Further suitable deuteration techniques are described in: Atzrodt J et al., Bioorg Med Chem, 20(18), 5658-5667, 2012; William JS et al., Journal of Labelled Compounds and Radiopharmaceuticals, 53(11-12), 635-644, 2010; Modvig A et al., J Org Chem, 79, 5861-5868, 2014. The content of deuterium can be determined, e.g., using mass spectrometry or NMR spectroscopy. Unless specifically indicated otherwise, it is preferred that the amino acid of the present invention or the compound of formula (I) is not enriched in deuterium. Accordingly, the presence of naturally occurring hydrogen atoms or1H hydrogen atoms in the amino acids of the present invention or the compounds of formula (I) is preferred. In one embodiment, particularly preferred are amino acids of the present invention or the compounds of formula (I) of the present invention, wherein the nitrogen atom in the amino group of the amino acid is15N-labeled. Enrichment in the15N can be achieved, for example, by starting from a starting material enriched in this isotope at a particular position. For a non-limiting example, it is possible to perform the reactions as shown in Scheme 1a hereinbelow starting from15N-labelled L-methionine, to obtain isotopically-labelled product. The amino acids of the present invention can be obtained according to the methods described hereinbelow and as described in, or per analogy to, the procedures shown in the Examples section. Synthetic routes for obtaining the compounds I and II, as indicated hereinabove, are shown in the following scheme 1a.

[0002] Scheme 1a According to the inventors, an inherent difficulty in such synthetic routes is to introduce the required functional groups in the appropriate order, relying on masked silanetriol groups to be eventually deprotected. Given the availability of allylglycine, the synthesis of Silamipate I by hydrosilylation was first attempted (Scheme 1a). L-allylglycine was quantitatively esterified using thionyl chloride in methanol to give 1, followed by amino group protection as benzyl carbamate (2, 91%). Several catalytic systems for the key hydrosilylation step were comparatively tried, the platinum-based Karstedt catalyst giving the best yield of the triethoxysilyl compound 3 (up to 70%). One-pot triple deprotection (triethoxysilane, N- carbamate, methyl ester) was performed with excellent yield by acid hydrolysis with 6N HCl. After freeze-drying, the target molecule I was obtained with a yield of 85%. A similar route was followed to synthesize Silamate II (Scheme 1a). Vinylglycine intermediate 7 was prepared in four steps from L-methionine according to the literature (A. Lumbroso, V. Coeffard, E. Le Grognec, I. Beaudet, J.-P. Quintard, Tetrahedron Letters 2010, 51, 3226–3228). After protection of the amino and carboxyl groups (5), oxidation of sulfur using sodium periodate yielded the corresponding sulfoxide 6. Thermal elimination of sulfenic acid in mesitylene gave the desired precursor 7 in 60% yield, which needed thorough purification prior to the hydrosilylation step. The latter proceeded smoothly to give 8 with a yield of 73%, accompanied in some reactions by the hydrogenation product (maximum 5%). In that case, careful separation of the two compounds by column chromatography was carried out, to avoid contamination of II by the amino acid norvaline. Finally, a triple deprotection as above gave the expected Silamate II with an excellent yield of 90%. Accordingly, the present invention provides a method for obtaining an amino acid of formula (Ia), wherein n is an integer ranging from 2 to 7, the method comprising the step of reacting the compound of formula (II): with HSi(OR)3 in the presence of a Karstedt catalyst. In formula (II), PG1 and PG2 are protecting groups for -NH2 and -COOH groups, respectively. The skilled person is capable of selecting suitable protecting groups that do not interfere with the reaction with HSi(OR)3, and at the same time can be removed efficiently to yield the desired product. Information and teaching with regard to the selection of particular protecting groups can be found in Greene's Protective Groups in Organic Synthesis, by Peter G. M. Wuts, and Theodora W. Greene, first published on 10 April 2006, DOI:10.1002 / 0470053488. Particularly suitable PG1is Cbz group. Cbz group is known to the skilled person, and is a group according to formula: Particularly suitable PG2is C1-6alkyl, for example ethyl or methyl, preferably methyl. In formula (I), each R is independently of each other selected from C1-6alkyl. Preferably, each R is ethyl. As it is to be understood herein, the method further comprises the step(s) of deprotecting - Si(OH)3, -NH2 and -COOH groups in the obtained product. This can be achieved, for example, by refluxing the compound for at least 30 minutes, preferably at least 1 hour, more preferably at least 2 hours, still more preferably for at least 4 hours (or about 4 hours) in 6N HCl in water. Alternatively, the compounds of the present invention can be obtained following the alkylation of Schiff base derivatives of glycine by the O'Donnell method seemed worth exploring (M. J. O’Donnell, J. M. Boniece, S. E. Earp, Tetrahedron Letters 1978, 19, 2641– 2644.), as shown in scheme 1b.

[0003] Scheme 1b Triallyl(iodomethyl)silane 10, obtained by the Finkelstein reaction on the corresponding chloride (E. Sh. Finkel’shtein, E. B. Portnykh, N. V. Ushakov, V. M. Vdovin, Russ Chem Bull 1981, 30, 483–487), was assayed as an electrophile bearing a masked silanetriol function. Indeed, triallylsilanes are known to convert into silanetriols through acid treatment (a) L. H. Sommer, L. J. Tyler, F. C. Whitmore, J. Am. Chem. Soc.1948, 70, 2872-2874; b) W.-C. Liao et al. Chem. Sci.2017, 8, 416-422.). The alkylation of the Schiff base 11 with 10 went smoothly. Hydrolysis with citric acid provided the free amine 13, and then with 6N HCl, in just one hour, the expected Silartate III under racemic form in 75% yield (Scheme 1b). Accordingly, the present invention further provides a method for obtaining an amino acid of formula (I), the method comprising the step of reacting LG-Z-CXY-Si(OR)3, with PGN-CH2-COO- PG2 pretreated with a base capable of generating PGN-CH--COO-PG2 carbanion. As discussed herein, Z, X and Y in LG-Z-CXY-Si(OR)3 are as in formula (I) hereinabove. LG in LG-Z-CXY-Si(OR)3 is a leaving group. The skilled person is capable of selecting appropriate leaving group. One preferred non-limiting example of the leaving group LG is iodo group (-I), PGN in LG-Z-CXY-Si(OR)3 is a protected -NH2 group. Preferably, PGN is (phenyl)2C=N-. PG2in LG-Z-CXY-Si(OR)3is a protecting group for -COOH group. Preferably, PG2is C1-6alkyl. Particularly suitable C1-6alkyl is tert-butyl. In LG-Z-CXY-Si(OR)3, rach R is independently of each other selected from C1-6alkyl and C2-6alkenyl. Preferably, each R is allyl As it is to be understood herein, the method further comprises the step(s) of deprotecting Si(OH)3, -NH2 and -COOH groups in the obtained product. This can be achieved, for example, by refluxing the compound for at least 30 minutes, preferably at least 1 hour, more preferably at least 2 hours, still more preferably for at least 4 hours (or about 4 hours) in 6N HCl in water. In a further embodiment, the present invention relates to a polypeptide comprising the amino acid of the present invention. The term “polypeptide” refers to a polymer of two or more amino acids linked via amide bonds that are formed between an amino group of one amino acid and a carboxylic acid group of another amino acid. The amino acids comprised in the polypeptide, which are also referred to as amino acid residues, may be selected from the 20 standard proteinogenic -amino acids (i.e., Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val), which can be present as the L-isomer or the D-isomer, and are preferably all present as the L-isomer, but also from non-proteinogenic and / or non-standard -amino acids (such as, e.g., ornithine, citrulline, homolysine, pyrrolysine, 4-hydroxyproline, -methylalanine (i.e., 2-aminoisobutyric acid), norvaline, norleucine, terleucine (tert-leucine), labionin, or an alanine or glycine that is substituted at the side chain with a cyclic group such as, e.g., cyclopentylalanine, cyclohexylalanine, phenylalanine, naphthylalanine, pyridylalanine, thienylalanine, cyclohexylglycine, or phenylglycine) as well as -amino acids (e.g., -alanine), -amino acids (e.g., -aminobutyric acid, isoglutamine, or statine) and -amino acids. The polypeptide may be unmodified or may be modified, e.g., at its N-terminus, at its C-terminus and / or at a functional group in the side chain of any of its amino acid residues (particularly at the side chain functional group of one or more Lys, His, Ser, Thr, Tyr, Cys, Asp, Glu, and / or Arg residues). Such modifications may include, e.g., the attachment of any of the protecting groups described for the corresponding functional groups in: Wuts PG & Greene TW, Greene’s protective groups in organic synthesis, John Wiley & Sons, 2006. Such modifications may also include the covalent attachment of one or more polyethylene glycol (PEG) chains (forming a PEGylated peptide), the glycosylation and / or the acylation with one or more fatty acids (e.g., one or more C8-30alkanoic or alkenoic acids; forming a fatty acid acylated peptide or protein). Moreover, such modified peptides or proteins may also include peptidomimetics, provided that they contain at least two amino acids that are linked via an amide bond (formed between an amino group of one amino acid and a carboxyl group of another amino acid). The amino acid residues comprised in the polypeptide may, e.g., be present as a linear molecular chain (forming a linear peptide) or may form one or more rings (corresponding to a cyclic peptide). The polypeptide may also form oligomers consisting of two or more identical or different molecules. The term “polypeptide” may also refer to a monovalent radical derived from a “polypeptide” as described herein above, wherein preferably an amino group or a carboxylic acid group, in particular the N-terminal amino group or the C-terminal carboxylic acid group, serves as point of attachment, preferably through an amide bond. Thus, the term “polypeptide” may refer to a polypeptidyl moiety attached to the rest of the molecule through a -CO- group (formed from a carboxylic acid group, e.g., from its C-terminal carboxylic acid group). As it is to be understood herein, the present invention further encompasses a monovalent or divalent radical derived from the amino acid of the present invention as described herein above, wherein preferably an amino group and / or a carboxylic acid group may serve as point(s) of attachment, preferably through an amide bond. Accordingly and preferably, the present invention relates to a polypeptide comprising a group of formula: , preferably a group of formula , wherein X, Y, and Z are as defined for formula (I). It is to be understood that at least one of - CO- and –NH- groups, preferably both -CO- and -NH- groups are involved in formation of peptide bonds with other amino acid residues. More preferably, the present invention relates to a polypeptide comprising a group of formula: wherein n and –(CH2)n– are as defined for formula (Ia). It is to be understood that at least one of -CO- and –NH- groups, preferably both -CO- and -NH- groups are involved in formation of peptide bonds with other amino acid residues. In certain embodiments, the polypeptide according to the present invention may comprise a single silanetriol amino acid according to the invention. Such a polypeptide is able to undergo a condensation reaction with another molecule or material comprising a suitable functional group, in particular a functional group that allows formation of a siloxane bond. In certain embodiments, the polypeptide according to the invention may comprise two or more silanetriol amino acids. Such a polypeptide may also undergo self-condensation to form an intramolecular siloxane Si-O cluster, which may, without limitation, result in new types of protein architectures. In certain embodiments, the polypeptide comprising one or more silanetriol amino acids according to the invention may be an isolated polypeptide. In certain embodiments, the polypeptide comprising one or more silanetriol amino acids according to the invention may be comprised in a protein complex. In certain embodiments, the polypeptide comprising one or more silanetriol amino acids according to the invention may be comprised in a particle, for example a viral particle, preferably a capsid protein of a viral particle. In certain embodiments, the polypeptide comprising one or more silanetriol amino acid according to the invention may be comprised in a cell. For example, the polypeptide comprising one or more silanetriol amino acid may be displayed on the surface of a cell such that the silanetriol amino acid is accessible to molecules in the exterior of the cell. Such cells may be immobilized on particles or surfaces comprising a suitable functional group, in particular a functional group that allows formation of a siloxane bond. Alternatively, such cells may be labelled via the silanetriol amino acid that is displayed on the cell surface. The cell may be any kind of cell. In a preferred embodiment, the cell is a microbial cell, such as a yeast cell or a bacterial cell. Accordingly, in a particular embodiment, the invention relates to a viral particle comprising the polypeptide according to the invention, i.e., a polypeptide comprising a silanetriol amino acid. Preferably, the polypeptide comprising the silanetriol amino acid is comprised in the capsid of the viral particle. In a particular embodiment, the invention relates to a cell comprising the polypeptide according to the invention, in particular wherein the polypeptide according to the invention is displayed on the surface of the cell. The cell may be any cell, i.e., may be eukaryotic or prokaryotic. In a preferred embodiment, the cell is a microbial cell, in particular a bacterial cell or a yeast cell. The skilled person is well aware of methods for displaying a polypeptide on the surface of a cell. In certain embodiments, the cell is an E. coli cell and the polypeptide displayed on the surface of the E. coli cell is a variant of the protein OmpC comprising a silanetrial amino acid according to the invention. In certain embodiments, the polypeptide may be an enzyme. The term “enzyme” as used herein, generally refers to a polypeptide which acts as a catalyst to induce a chemical change in compounds or “substrates”. In certain embodiments, an enzyme comprising one or more silanetriol amino acids according to the invention may be conjugated to another molecule or material via the one or more silanetriol amino acids, preferably wherein the silanetriol undergoes a condensation reaction with a suitable functional group present in said other molecule or material. More preferably, the functional group is a functional group that allows formation of a siloxane bond. In certain embodiments, one or more silanetriol amino acid according to the invention may be comprised in the active center of an enzyme. In certain embodiments, the one or more silanetriol amino acid according to the invention may be a catalytic residue of the enzyme. In certain embodiments, a polypeptide comprising one or more silanetriol amino acids according to the invention may be immobilized on a solid material. The term solid, as used herein, may in particular mean that the material concerned has a substantially homogenous and / or dense structure or texture. In certain embodiments, the solid may be artificially coated with a molecule or material comprising a functional group that allows for the formation of a siloxane bond. In certain embodiments, the solid may be made of a material that comprises functional groups that allow for the formation of a siloxane bond. For example, materials, such as concrete, may be coated with silicic acid, silicate salts, or other compounds containing silanol, silanediol, or silanetriol groups. In certain embodiments, a material, such as concrete, may be coated with a silane / siloxane sealer. In certain embodiments, the solid may be a surface. The term "surface" as used herein refers to the exterior or external part or layer of an object or molecule. In certain embodiments, the solid may be a particle. The term "particle" as used herein refers to a solid phase such as colloidal particles, microspheres, nanoparticles, or beads. Within the present invention, it is contemplated that silanetriol amino acids or polypeptides comprising silanetriol amino acid can condensate with other molecules or materials to form a siloxane bond. For that, the other molecule has to comprise a functional group that allows for the formation of a siloxane bond. Functional groups that allow for the formation of a siloxane bond may be comprised, without limitation, in silanols, including silanediols, silanetriols and silicic acids, or salts thereof. The silicic acid may be orthosilicic acid (Si(OH)4), metasilicic acid (SiO(OH)2),pyrosilicic acid (OSi(OH)3)2), or disilicic acid (Si2O3(OH)2). In a preferred embodiment, the molecule comprising the functional group that allows the formation of a siloxane bond is orthosilicic acid (Si(OH)4). Condensation of molecules comprising these functional groups with a silanetriol amino acid according to the invention will result in the formation of a siloxane bond (Si-O-Si). Within the present invention, the term “siloxane bond” is to be interpreted broadly and encompasses further bonds comprising silicon-oxygen linkages. For example, the silanetriol amino acid according to the invention may condensate with boric acid (B(OH)3) or borate salts, resulting in the formation of borosiloxane bond (Si-O-B). Moreover, the silanetriol amino acid according to the invention may condensate with phosphate salts of phosphoric acid (P(O)(OH)3), resulting in the formation of phosphosiloxane bond (Si-O-P). Accordingly, a functional group that allows formation of a siloxane bond is preferably an OH group comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, boric acid, a borate salt, or a phosphate salt of phosphoric acid. Thus, in a particular embodiment, the invention relates to the polypeptide according to the invention, wherein the functional group that allows for the formation of a siloxane bond is comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, boric acid, a borate salt, or a phosphate salt of phosphoric acid. In a particularly preferred embodiment, polypeptides comprising a silanetriol amino acid according to the invention can undergo formation of a siloxane bond with materials comprising silicic acid molecules or silicate salts. Materials comprising silicic acid molecules or silicate salts are preferably mineral material such as, without limitation, glass, silica, concrete, ceramics, zeolites, and clays. Thus, in a particular embodiment, the invention relates to the polypeptide according to the invention, wherein the solid comprises or consists of a mineral material, in particular wherein the mineral material comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays. Within the present invention, the term “mineral material” refers to naturally occurring or synthetically produced substances that are solid under standard ambient temperature and pressure (SATP) which refers to a temperature of 25°C and an absolute pressure of exactly 100 kPa. The naturally occurring substances are inorganic and have a crystal structure or are amorphous. Herein, it is preferred that the mineral material comprises a silicic acid or a silicate salt that can undergo formation of a siloxane bond with the silanetriol group of the amino acid according to the invention. That is, amino acids comprising a silanetriol functional group may be used for the immobilization of biological agents onto otherwise inert mineral surfaces for various purposes including, without limitation, purification or biocatalysis, such as heterogenous catalysis. As mentioned herein above, for that purpose, the amino acid comprising the silanetriol functional group may be comprised, without limitation, in a polypeptide, an enzyme, a virus particle or a cell. Moreover, amino acids comprising a silanetriol functional group may be used for functionalizing inert mineral surfaces or particles. For example, functionalizing an otherwise inert mineral surface or particle with the amino acid according to the invention may confer the surface or particle with biologically active functional groups (COOH, NH2). Furthermore, mineral surfaces or particles may be functionalized with macromolecules (polypeptides, proteins, enzymes, protein complexes), viral particles or even entire cells comprising the amino acid according to the invention. Within the present invention, amino acids, macromolecules, viral particles and cells may also be referred to as biological agents. Accordingly, in a particular embodiment, the invention relates to a solid surface or particle covalently linked to the amino acid according to the invention or the polypeptide according to the invention, wherein the amino acid or the polypeptide is covalently linked to the surface or the particle via a siloxane bond, in particular wherein the siloxane bond comprises the structure (Si-O-Si), (Si-O-B) or (Si-O-P). In a particular embodiment, the invention relates to the solid surface or particle according to the invention, wherein the surface or particle comprises a molecule selected from the group consisting of: a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, and a phosphate salt of phosphoric acid. In a particular embodiment, the invention relates to the solid surface or particle according to the invention, wherein the surface or particle comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays. In one non-limiting example, amino acids comprising a silanetriol functional group may be used in functionalizing buildings or parts of buildings with biological agents. That is, biological agents comprising or consisting of the amino acid or the peptide according to the invention may be coupled to parts of a building that comprise a functional group that allows formation of a siloxane bond, such as, without limitation, elements made of glass or concrete. This may have various applications, including strategies to make buildings more resilient or to improve the air quality in buildings. In another non-limiting example, amino acids comprising a silanetriol functional group may be used in functionalizing the interior of pipes, such as concrete pipes, with biological agents. That is, biological agents comprising or consisting of the amino acid or the peptide according to the invention may be coupled to the interior wall of a pipe if the interior wall of the pipe comprises a functional group that allows formation of a siloxane bond. Such a functional group may inherently be comprised in concrete pipes. Alternatively, pipes may be coated with a material that allows formation of a siloxane bond with the silanetriol amino acid according to the invention. Without limitation, pipes may be functionalized with enzymes or cells that assist in wastewater treatment. In a particular embodiment, the invention relates to a siloxane (Si-O) cluster comprising the amino acid according to the invention and / or the polypeptide according to the invention. Within the present invention, a siloxane cluster is defined as a molecular structure composed of silicon (Si), oxygen (O), and occasionally other elements (e.g., B or P), typically forming a three-dimensional network. These clusters comprise one or more siloxane bonds (e.g., Si-O- Si, Si-O-B, Si-O-P) and may have various organic or inorganic groups attached to the silicone (or B or P) atoms. The siloxane cluster may be formed between two or more amino acids and / or peptides according to the invention. Alternatively, or in addition, the siloxane cluster may comprise additional binding partners that can contribute to the formation of the siloxane cluster. In certain embodiments, the additional binding partner comprises silanols, including silanediols, silantriols and silicic acids, or salts thereof, boric acid, borate salts, or phosphate salts of phosphoric acid. In certain embodiments, the siloxane cluster may be formed between one or more amino acids according to the invention and a surface or particle comprising a functional group that allows for the formation of a siloxane bond. In certain embodiments, the siloxane cluster may be formed between one or more polypeptides according to the invention and a surface or particle comprising a functional group that allows for the formation of a siloxane bond. As mentioned above, the polypeptide may also be part of a larger entity, such as a viral particle or a cell. In certain embodiments, the siloxane cluster may be formed between one or more amino acids and / or peptides according to the invention, and a glass particle or surface. That is, the silanetriol functional group of the amino acid or peptide according to the invention may be used to immobilize polypeptides, enzymes, viral particles or cells on a glass particle or surface. Alternatively, glass particles or surfaces may be functionalized with the amino acid or polypeptide according to the invention. An example for the functionalization of glass surfaces with silanetriols has been provided by Spirk at al. (ACS Appl Mater Interfaces, 2010, 2(10):2956-62. In certain embodiments, the glass surface may be a glass surface of a laboratory equipment, such as, without limitation, a test tube, a flask, a beaker or a microscope slide. In certain embodiments, the glass surface may be a window of a building or a vehicle, including cars, busses, trains, etc. In another embodiment, the siloxane cluster according to the invention may be formed between one or more amino acids and / or peptides according to the invention, and a surface made of a mineral material and comprising a functional group that allows for the formation of a siloxane bond, including, without limitation concrete, ceramics, zeolites, and clays. In certain embodiments, the siloxane cluster may be formed between one or more amino acids and / or peptides according to the invention, and the interior of a concrete pipe or a pipe that has been coated with a material comprising a function group that allows formation of a siloxane bond. It is to be understood that the amino acid according to the invention can directly undergo a condensation reaction with mineral materials comprising a suitable functional group. However, these surfaces may further be coated with another material to facilitate formation of the siloxane cluster, such as a material comprising the reactive groups disclosed herein. In a particular embodiment, the invention relates to a method of immobilizing a polypeptide on a solid, the method comprising the steps of: a) providing a solid comprising a functional group that is suitable for the formation of a siloxane bond; b) contacting the solid of step (a) with the polypeptide according the invention; c) immobilizing the polypeptide to the solid. In a particular embodiment, the invention relates to a method of equipping a solid with a biological agent, the method comprising the steps of: a) providing a solid comprising a functional group that allows for the formation of a siloxane bond; b) equipping the solid with a biological agent by contacting the solid of step (a) with the amino acid according to the invention or the polypeptide according to the invention. In a particular embodiment, the invention relates to the method according to the invention, wherein the solid is a surface or a particle. In a particular embodiment, the invention relates to the method according to the invention, wherein the functional group that allows for the formation of a siloxane bond is comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, or a phosphate salt of phosphoric acid. In a particular embodiment, the invention relates to the method according to the invention, wherein the solid comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays. The skilled person is aware of conditions that are suitable for the formation of siloxane bonds. Preferably, spontaneous condensation of silanetriols or other suitable compounds takes place under alkaline conditions. In a particular embodiment, the invention relates to an aminoacylated tRNA comprising the amino acid according to the invention. The aminoacylated tRNA comprising the amino acid according to the invention may serve as substrate for a ribosome and may thus be used to incorporate the amino acid according to the invention into a polypeptide. Any one of the silanetriol amino acids disclosed herein may be attached to a tRNA. Preferably the amino acid according to the invention is attached to a tRNA via its carboxy group, as known in the art. Attachment of an amino acid according to the invention to a tRNA may be achieved with an engineered aminoacyl-tRNA synthetase that specifically recognizes the amino acid according to the invention, as described, inter alia, by Krahn et al. (Enzymes, 2020, 48:351- 395. doi: 10.1016 / bs.enz.2020.06.004) or in the appended Example 4. Alternatively, the flexizyme approach may be used to attach an amino acid according to the invention to a tRNA as described, inter alia, by Lee et al. (Nat Commun, 2019, 10(1):5097. doi: 10.1038 / s41467- 019-12916-w). The tRNA may be any tRNA. However, it is preferred that the tRNA is an orthogonal tRNA. In particular the tRNA may comprise one or more mutations in the acceptor stem and / or the anticodon region to allow site specific incorporation into a polypeptide by the ribosome in a cell; see Krahn et al. (Enzymes, 2020, 48:351-395. doi: 10.1016 / bs.enz.2020.06.004). Thus, in a particular embodiment, the invention relates to a method of producing a polypeptide comprising a silanetriol amino acid at a specified position in a cell, the method comprising: a) growing, in an appropriate medium, the cell, wherein the cell comprises a nucleic acid that encodes the polypeptide, and wherein the nucleic acid comprises at least one selector codon; and b) providing the amino acid according to the invention; wherein the cell further comprises: c) a nucleic acid sequence encoding an orthogonal aminoacyl-tRNA synthetase (O-RS), and, d) an orthogonal tRNA (O-tRNA), that recognizes the selector codon, wherein said O—RS aminoacylates the O-tRNA with the amino acid according to the invention. The skilled person is well aware of methods to introduce non-natural amino acids into polypeptides with an orthogonal tRNA / aminoacyl-tRNA synthetase (O-tRNA / O-RS) pair. For example, the introduction of non-natural amino acids into polypeptides with an O-tRNA / O-RS pair is disclosed in WO 2010 / 037062, which is incorporated herein by reference in its entirety. The translational components used in the present invention are typically derived from non- eukaryotic organisms. For example, the orthogonal O-tRNA can be derived from a non- eukaryotic organism, e.g., an archaebacterium, such as Methanococcus jannaschii, Methanobacterium thermoautotrophicum, Halobacterium such as Haloferax volcanii and Halobacterium species NRC-1, Archaeoglobus fulgidus, Pyrococcus furiosus, Pyrococcus horikoshii, Aeuropyrum pernix, or the like, or a eubacterium, such as Escherichia coli, Thermus thermophilus, Bacillus stearothermphilus, or the like, while the orthogonal O-RS can be derived from a non-eukaryotic organism, e.g., Methanobacterium thermoautotrophicum, Halobacterium such as Haloferax volcanii and Halobacterium species NRC-1, Archaeoglobus fulgidus, Pyrococcus furiosus, Pyrococcus horikoshii, Aeuropyrum pernix, or the like, or a eubacterium, such as Escherichia coli, Thermus thermophilus, Bacillus stearothermphilus, or the like. In one embodiment, eukaryotic sources can also be used, including but not limited to, plants, algae, protists, fungi, yeasts, animals (e.g., mammals, insects, arthropods, etc.), or the like. The individual components of an O-tRNA / O-RS pair can be derived from the same organism or different organisms. In one embodiment, the O-tRNA / O-RS pair is from the same organism. Alternatively, the O-tRNA and the O-RS of the O-tRNA / O-RS pair are from different organisms. The O-tRNA, O-RS or O-tRNA / O-RS pair can be selected or screened in vivo or in vitro and / or used in a cell, e.g., a non-eukaryotic cells (such as E. coli cell), or a eukaryotic cell, to produce a polypeptide with an amino acid according to the invention. A non-eukaryotic cell can be from a variety of sources, such as the Axchaea phylogenetic domain, including but not limited to, Methanococcus jannaschii, Methanobacterium thermoautotrophicum, Halobacterium such as Haloferax volcanii and Halobacterium species NRC-1, Archaeoglobus fulgidus, Pyrococcus furiosus, Pyrococcus horikoshii, Aeuropyrum pernix, or the like, or can belong to the Eubacteria phylogenetic domain (including but not limited to, Escherichia coli, Thermus thermophilus, Bacillus stearothermophilus, Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas putida, etc.), or the like. A eukaryotic cell can be from a variety of sources, including but not limited to, a plant (e.g., complex plant such as monocots, or dicots), an algae, a protist, a fungus, a yeast (including but not limited to, Saccharomyces cerevisiae), an animal (including but not limited to, a mammal, an insect, an arthropod, etc.), or the like. Compositions of cells with translational components of the present invention are also a feature of the present invention. See also U.S. Ser. No.10 / 825,867 entitled “Expanding the Eukaryotic Genetic Code” for screening O-tRNA and / or O-RS in one species for use in another species. To express a polypeptide of interest with an amino acid according to the invention in a host cell, one may subclone polynucleotides encoding a polypeptide of interest into an expression vector that contains a promoter to direct transcription, a transcription / translation terminator, and if for a nucleic acid encoding a protein, a ribosome binding site for translational initiation. Suitable bacterial promoters are well known in the art. Bacterial expression systems for expressing a polypeptide of interest are available in, including but not limited to, E. coli, Bacillus sp., Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas putida, and Salmonella. Kits for such expression systems are commercially available. Eukaryotic expression systems for mammalian cells, yeast, and insect cells are well known in the art and are also commercially available. A tRNA and / or RS and / or a polypeptide of interest may be utilized and / or expressed in any number of suitable expression systems including, for example, yeast, insect cells, mammalian cells, and bacteria. As used herein, the term “orthogonal” refers to a molecule (e.g., an orthogonal tRNA (O-tRNA) and / or an orthogonal aminoacyl tRNA synthetase (O-RS)) that is used with reduced efficiency by a system of interest (e.g., a translational system, e.g., a cell). Orthogonal refers to the inability or reduced efficiency, e.g., less than 20% efficient, less than 10% efficient, less than 5% efficient, or e.g., less than 1% efficient, of an orthogonal tRNA and / or orthogonal RS to function in the translation system of interest. For example, an orthogonal tRNA in a translation system of interest is aminoacylated by any endogenous RS of a translation system of interest with reduced or even zero efficiency, when compared to aminoacylation of an endogenous tRNA by an endogenous RS. In another example, an orthogonal RS aminoacylates any endogenous tRNA in the translation system of interest with reduced or even zero efficiency, as compared to aminoacylation of the endogenous tRNA by an endogenous RS. A second orthogonal molecule can be introduced into the cell that functions with the first orthogonal molecule. For example, an orthogonal tRNA / RS pair includes introduced complementary components that function together in the cell with an efficiency (e.g., about 50% efficiency, about 60% efficiency, about 70% efficiency, about 75% efficiency, about 80% efficiency, about 85% efficiency, about 90% efficiency, about 95% efficiency, or about 99% or more efficiency) to that of a corresponding tRNA / RS endogenous pair. The term “selector codon” refers to codons recognized by the O-tRNA in the translation process and not recognized by an endogenous tRNA. The O-tRNA anticodon loop recognizes the selector codon on the mRNA and incorporates its amino acid, e.g., an amino acid according to the invention, at this site in the polypeptide. Selector codons can include but are not limited to, e.g., nonsense codons, such as, stop codons, including but not limited to, amber, ochre, and opal codons; four or more base codons; rare codons; codons derived from natural or unnatural base pairs and / or the like. For a given system, a selector codon can also include one of the natural three base codons, wherein the endogenous system does not use (or rarely uses) said natural three base codon. For example, this includes a system that is lacking a tRNA that recognizes the natural three base codon, and / or a system wherein the natural three base codon is a rare codon. A suppressor tRNA is a tRNA that alters the reading of a messenger RNA (mRNA) in a given translation system, e.g., by providing a mechanism for incorporating an amino acid into a polypeptide chain in response to a selector codon. For example, a suppressor tRNA can read through a codon including but not limited to, a stop codon, a four base codon, or a rare codon. As used herein, the term “medium” or “media” includes any culture medium, solution, solid, semi-solid, or rigid support that may support or contain any host cell, including bacterial host cells, yeast host cells, insect host cells, plant host cells, eukaryotic host cells, mammalian host cells, CHO cells, prokaryotic host cells, E. coli, or Pseudomonas host cells, and cell contents. Thus, the term may encompass medium in which the host cell has been grown, e.g., medium into which a culture or whole organism or cell is growing, and the medium may have a non- natural amino acid included to support growth of replication deficient organisms or cells, including medium either before or after a proliferation step. The term also may encompass buffers or reagents that contain host cell lysates, such as in the case where the antigens are produced intracellularly and the host cells are lysed or disrupted to release the antigens or recombinant antigens. The term “nucleic acid” refers to deoxyribonucleotides, deoxyribonucleosides, ribonucleosides, or ribonucleotides and polymers thereof in either single- or double-stranded form. Unless specifically limited, the term encompasses nucleic acids containing known analogues of natural nucleotides which have similar binding properties as the reference nucleic acid and are metabolized in a manner similar to naturally occurring nucleotides. Unless specifically limited otherwise, the term also refers to oligonucleotide analogs including PNA (peptidonucleic acid), analogs of DNA used in antisense technology (phosphorothioates, phosphoroamidates, and the like). Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (including but not limited to, degenerate codon substitutions) and complementary sequences as well as the sequence explicitly indicated. Specifically, degenerate codon substitutions may be achieved by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed-base and / or deoxyinosine residues (Batzer et al., Nucleic Acid Res. 19:5081 (1991); Ohtsuka et al., J. Biol. Chem.260:2605-2608 (1985); Rossolini et al., Mol. Cell. Probes 8:91-98 (1994)). In the absence of a suitable aminoacyl-rRNA synthetase that is suitable to attach an amino acid according to the invention to a tRNA, polypeptides comprising the amino acid according to the invention may also be synthesized chemically as known in the art, for example as disclosed by Tan et al. (J Am Chem Soc, 2020, doi: 10.1021 / jacs.0c09664) The following definitions apply throughout this specification and claims, unless explicitly indicated to the contrary. The term “hydrocarbon group” refers to a group consisting of carbon atoms and hydrogen atoms. As used herein, the term “alkyl” refers to a monovalent saturated acyclic (i.e., non-cyclic) hydrocarbon group which may be linear or branched. Accordingly, an “alkyl” group does not comprise any carbon-to-carbon double bond or any carbon-to-carbon triple bond. A “C1- 5 alkyl” denotes an alkyl group having 1 to 5 carbon atoms. Preferred exemplary alkyl groups are methyl, ethyl, propyl (e.g., n-propyl or isopropyl), or butyl (e.g., n-butyl, isobutyl, sec-butyl, or tert-butyl). Unless defined otherwise, the term “alkyl” preferably refers to C1-4 alkyl, more preferably to methyl or ethyl, and even more preferably to methyl. As used herein, the term “alkenyl” refers to a monovalent unsaturated acyclic hydrocarbon group which may be linear or branched and comprises one or more (e.g., one or two) carbon- to-carbon double bonds while it does not comprise any carbon-to-carbon triple bond. The term “C2-5alkenyl” denotes an alkenyl group having 2 to 5 carbon atoms. Preferred exemplary alkenyl groups are ethenyl, propenyl (e.g., prop-1-en-1-yl, prop-1-en-2-yl, or prop-2-en-1-yl), butenyl, butadienyl (e.g., buta-1,3-dien-1-yl or buta-1,3-dien-2-yl), pentenyl, or pentadienyl (e.g., isoprenyl). Unless defined otherwise, the term “alkenyl” preferably refers to C2-4alkenyl. As used herein, the term “alkylene” refers to an alkanediyl group, i.e. a divalent saturated acyclic hydrocarbon group which may be linear or branched. A “C1-5alkylene” denotes an alkylene group having 1 to 5 carbon atoms, and the term “C0-3 alkylene” indicates that a covalent bond (corresponding to the option “C0alkylene”) or a C1-3alkylene is present. Preferred exemplary alkylene groups are methylene (-CH2-), ethylene (e.g., -CH2-CH2- or -CH(-CH3)-), propylene (e.g., -CH2-CH2-CH2-, -CH(-CH2-CH3)-, -CH2-CH(-CH3)-, or -CH(-CH3)- CH2-), or butylene (e.g., -CH2-CH2-CH2-CH2-). Unless defined otherwise, the term “alkylene” preferably refers to C1-4 alkylene (including, in particular, linear C1-4 alkylene), more preferably to methylene or ethylene, and even more preferably to methylene. As used herein, the term “halogen” refers to fluoro (-F), chloro (-Cl), bromo (-Br), or iodo (-I). The terms “bond” and “covalent bond” are used herein synonymously, unless explicitly indicated otherwise or contradicted by context. As used herein, the terms “optional”, “optionally” and “may” denote that the indicated feature may be present but can also be absent. Whenever the term “optional”, “optionally” or “may” is used, the present invention specifically relates to both possibilities, i.e., that the corresponding feature is present or, alternatively, that the corresponding feature is absent. For example, the expression “X is optionally substituted with Y” (or “X may be substituted with Y”) means that X is either substituted with Y or is unsubstituted. Likewise, if a component of a composition is indicated to be “optional”, the invention specifically relates to both possibilities, i.e., that the corresponding component is present (contained in the composition) or that the corresponding component is absent from the composition. Various groups are referred to as being “optionally substituted” in this specification. Generally, these groups may carry one or more substituents, such as, e.g., one, two, three or four substituents. It will be understood that the maximum number of substituents is limited by the number of attachment sites available on the substituted moiety. Unless defined otherwise, the “optionally substituted” groups referred to in this specification carry preferably not more than two substituents and may, in particular, carry only one substituent. Moreover, unless defined otherwise, it is preferred that the optional substituents are absent, i.e. that the corresponding groups are unsubstituted. A skilled person will appreciate that the substituent groups comprised in the compounds of the present invention may be attached to the remainder of the respective compound via a number of different positions of the corresponding specific substituent group. Unless defined otherwise, the preferred attachment positions for the various specific substituent groups are as illustrated in the examples. As used herein, unless explicitly indicated otherwise or contradicted by context, the terms “a”, “an” and “the” are used interchangeably with “one or more” and “at least one”. Thus, for example, a composition comprising “a” compound of formula (I) can be interpreted as referring to a composition comprising “one or more” compounds of formula (I). As used herein, the term “comprising” (or “comprise”, “comprises”, “contain”, “contains”, or “containing”), unless explicitly indicated otherwise or contradicted by context, has the meaning of “containing, inter alia”, i.e., “containing, among further optional elements, …”. In addition thereto, this term also includes the narrower meanings of “consisting essentially of” and “consisting of”. For example, the term “A comprising B and C” has the meaning of “A containing, inter alia, B and C”, wherein A may contain further optional elements (e.g., “A containing B, C and D” would also be encompassed), but this term also includes the meaning of “A consisting essentially of B and C” and the meaning of “A consisting of B and C” (i.e., no other components than B and C are comprised in A). The invention will be illustrated in the following examples. These are not to be construed as limiting in any way, but merely serve the purpose of illustrating the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1: Silanetriol amino acids: background and opportunities. Fig.2:29SiNMR evidence for siloxane crosslinking by Silamate II upon increasing concentration. Other parameters such as temperature, pH and time are identical (pH<2, 20°C, 0 day). Fig.3:1H NMR monitoring spectra of II at t = 0 min, 2 days and 16 days. Fig.4:1H NMR monitoring spectra of II (concentration dependence at t=0 min). Fig.5:1H NMR monitoring spectra of II (concentration dependence at t=16 days). Fig.6: Experimental data and fitted curves of II at t=0. Fig.7: Experimental data and fitted curves of II at t=16 days. Fig.8:13C NMR monitoring spectra of II (pH = 1). Fig.9:13C NMR monitoring spectra of II (pH = 11). Fig.10:29Si monitoring spectra of II (pH = 1). Fig.11:29Si monitoring spectra of II (pH = 11). Fig.12: Growth curves of bacterial strains Acinetobacter baylyi ADP1 and Pseudomonas putida KT2440 with Silaglutamate, in comparison with Glutamate and Ammonium Chloride. (The x- axis shows time in minutes and the y-axis shows optical density at 600 nanometers.) Fig.13: Improved growth on Silaglutamate of bacterial strains Acinetobacter baylyi ADP1 and Pseudomonas putida KT2440 in serial cultures. (The x-axis shows time in minutes and the y- axis shows optical density at 600 nanometers. Three iterative inoculations are shown for each of the two strains.)

[0004] EXAMPLES Herein the inventors report the chemical syntheses of three amino acids equipped with a side chain ending with the silanetriol group (I-III, see Figure 1) as analogs of the simplest L-2-amino diacids, respectively aminoadipate, glutamate and aspartate (the two latter belonging to the canonical set of protein monomers and the former serving as intermediate in the lysine biosynthetic pathway of certain species). Following thorough structural and biochemical protocols, the three novel silanetriol amino acids were demonstrated to undergo enzymatic transamination and to generate the corresponding silanetriol oxo acids. Materials and methods General experimental information. Chemicals were purchased from common commercial suppliers (Sigma-Aldrich, Fluorochem, Alfa Aesar, and Acros Organics) and distilled if necessary. All solvents were of extra-dried grade or distilled prior to use. Triethylsilane was purchased from Sigma-Aldrich and was distilled before use. Reactions requiring inert conditions were carried out in flame-dried glassware under an argon atmosphere. Thin layer chromatography (TLC) analyses were performed on Merck 60 F254 silica gel pre-coated aluminum-backed plates with a layer thickness of 200 m. Product spots were visualized under UV light ( max = 254 nm) and / or by staining with a potassium permanganate solution. Flash column chromatographies were conducted on Silica gel 60 M, 0.04–0.063 mm, from Macherey Nagel. NMR spectra were recorded at room temperature on a Bruker Avance-I-400 and Bruker Avance-II-300 spectrometers as well as 600 MHz Bruker Avance III. For the monitoring of the formation of oligomers of silamate II vs concentration and time, NMR spectra were recorded on a Bruker, 500 MHz, AVANCE NEO console equipped with the TXI (1H,15N) or BBO (29Si) probe.1H NMR spectra were calibrated on a non-deuterated solvent residual peak (7.26 ppm for CHCl3, 2.50 ppm for DMSO- d6, 4.79 ppm for H2O).13C NMR spectra were referenced at 77.16 ppm for CDCl3. 39.52 ppm for DMSO- d6. Chemical shifts are reported in parts per million ( ) and coupling constants (J) are given in Hertz (Hz). Splitting patterns are indicated as follows: br, broad; s,singlet; d, doublet; t, triplet; q, quartet; m, multiplet. High resolution mass spectrometry was performed on a Bruker microTOF (ESI and APCI). Melting points (M.p.) were determined with a Stuart Scientific SMP3 melting point apparatus and are not corrected. -Values were measured on a P-2000 Digital Polarimeter from Jasco in a cuvette (l = 1 cm) at 589 nm (Na lamp). Concentration c was given in g / 100 mL. Compound names were generated by the computer program ChemDraw according to the guidelines specified by the International Union of Pure and Applied Chemistry (IUPAC). For transamination studies, ATA (T7684-10mg, Lot # 097H1003) and Pyridoxal phosphate (P3657-1G; Source: SLCL8133) were purchased from Sigma-Aldrich. The enzyme powder and le Pyridoxal phosphate were stored at -18 °C before use. General procedure for hydrosilylation. To a solution of alkene 2 or 7 (1 equiv.) in tetrahydrofuran (0.1 M) at room temperature were added triethoxysilane (1.5 equiv.) and 0.01 equiv. Karstedt catalyst (platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, 2% of Pt in xylenes). The reaction was stirred at 60 °C for 16 h. The reaction was evaporated to dryness and the black residue was purified by flash chromatography on silica to afford the desired products after drying under pressure (slightly yellow oils, 1.33 g of 3, 79% yield or 1.18 g of 8, 75% yield). General procedure for hydrolysis. To an aqueous hydrochloric solution (6N, 17 mL) at gentle reflux (heating 115 °C) was added a solution of 3 or 8 in methanol and the reaction mixture was stirred at reflux for 4 h in the open air. The clear solution was cooled down to room temperature, degassed by bubbling of argon and lyophilised to give a pure white solid (182 mg of I, 96% yield or 142 mg of II, 90% yield). General procedure for transamination. Triethanolamine buffer solution preparation: to a 30 mL beaker equipped with a magnetic stirrer, HPLC grade water (10.0 mL), triethanolamine (0,250 g), s(4 mg) were added. Under gentle stirring at rt, concentrated HCl was added dropwise. After pH reached 7.5 (indicated by a pH meter), the total volume was then adjusted to 15.0 mL by adding HPLC grade water. The buffer solution was used directly for transamination. To a 5 mL vial equipped with a magnetic stir bar was added the Silanetriol amino acid (0.01 mmol) and the oxoglutarate (1.46 mg, 0.01 mmol). The triethanolamine buffer at pH = 7.5 (1.0 mL) and the transaminase (1.0 mg) were then added sequentially. The reaction vial was capped by a screw cap and stirred vigorously (1000 rpm) at 37oC for 24 h. After 24h, the reaction was filtered through a PTFE membrane 0.2 m and directly analyzed by ultrahigh- resolution mass spectrometry Synthesis of Silamipate I General procedure for 1 To a suspension of L-allylglycine (500 mg, 4.34 mmol, 1.0 equiv.) in methanol (10 mL) at 0 °C was added dropwise thionyl chloride (0.48 mL, 6.51 mmol, 1.5 equiv.). The reaction mixture was stirred at 0 °C for 5 min then at room temperature for 16 h. The reaction was evaporated to dryness and dried under high vacuum to afford to the solid compound (white solid, 719 mg, quantitative yield).1H NMR (400 MHz, DMSO-d6): =8.73 (s, 3H), 5.78 (ddt,3JH-H = 17.2, 10.1, 7.1 Hz, 1H), 5.25 – 5.08 (m, 2H), 4.09 (t,3JH-H = 6.0 Hz, 1H), 3.72 (s, 3H), 3.33 (s, 1H), 2.61 (t,3JH-H = 6.5 Hz, 2H);13C NMR (100 MHz, DMSO-d6): =169.3, 131.3, 119.9, 52.6, 51.6, 34.2. These data are in agreement with those previously reported (N. Dalton, C. P. Gordon, T. P. Boyle, N. Vandegraaf, J. Deadman, D. I. Rhodes, J. A. Coates, S. G. Pyne, P. A. Keller, J. B. Bremner, Organic & Biomolecular Chemistry.2016, 14, 6010-6023). General procedure for 2 To a mixture of 1 (719 mg, 4.34 mmol) and sodium hydrogenocarbonate (1.09 g, 13.0 mmol) in a mixture of tetrahydrofuran (4 mL) and water (4 mL) at room temperature was added slowly benzyl chloroformate (0.67 mL, 4.78 mmol). The reaction was stirred at room temperature for 6h. The reaction was quenched with a saturated aqueous solution of ammonium chloride (50 mL) and the aqueous layer was extracted with dichloromethane (3 x 50 mL). The combined organic layers were dried over magnesium sulphate, filtered and evaporated under pressure. The residue was purified by flash chromatography on silica gel to afford the expected compound 2 (colorless oil, 1.04 g, 91% yield). Rf=0.27 (Petet / Et2O 8:2) ;1H NMR (400 MHz, CDCl3): =7.40 – 7.27 (m, 5H), 5.76 – 5.61 (m, 1H), 5.36 (d, J = 8.2 Hz, 1H), 5.17 – 5.10 (m, 1H), 5.11 – 5.08 (m, 3H), 4.46 (q, J = 6.1 Hz, 1H), 3.74 (s, 3H), 2.63 – 2.42 (m, 2H);13C NMR (100 MHz, CDCl3): =172.2, 155.8, 136.3, 132.1, 128.6 (2C), 128.2, 128.2 (2C), 119.4, 67.1, 53.4, 52.4, 36.8. These data are in agreement with those previously reported (G. Z. Elek, K. Koppel, D. M. Zubrytski, N. Konrad, I. Järving, M. Lopp, D. G. Kananovich, Org. Lett.2019, 21, 8473-8478). General procedure for 3 To a solution of alkene 2 (1.04 g, 3.95 mmol) in tetrahydrofuran (40 mL) at room temperature were added triethoxysilane (1.09 mL, 5.93 mmol) and Karstedt catalyst (2% of Pt in xylenes, 0.45 mL, 0.04 mmol). The reaction was stirred at 60 °C for 16 h. The reaction was evaporated to dryness and the black residue was purified by flash chromatography on silica to afford to the compound after drying under pressure (slightly yellow oil, 1.33 g, 79% yield). Rf=0.24 (Tol / Et2O / Si(OCH3)49:1:0.05);1H NMR (400 MHz, CDCl3): = 7.38 – 7.28 (m, 5H), 5.27 (d,3JH-H = 8.1 Hz, 1H), 5.10 (s, 2H), 4.37 (q,3JH-H = 7.8 Hz, 1H), 3.80 (q,3JH-H = 7.0 Hz, 6H), 3.73 (s, 3H), 1.93 – 1.79 (m, 1H), 1.77 – 1.64 (m, 1H), 1.54 – 1.42 (m, 2H), 1.21 (t,3JH-H = 7.0 Hz, 9H), 0.71 – 0.57 (m, 2H);13C NMR (100 MHz, CDCl3): = 173.2, 156.0, 136.5, 128.7 (2C), 128.3, 128.2 (2C), 67.1, 58.5 (3C), 53.8, 52.4, 35.7, 19.0, 18.4 (2C), 10.1;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 3.80 / -45.92; HRMS (ESI): m / z calcd for C20H33NO7SiH: 428.2099 [M+H]+; found 428.2083; [ ].= 7.6 (c = 1.00 in CHCl3). General procedure for I To an aqueous hydrochloric solution (6N, 17 mL) at gentle reflux (heating 115 °C) was added a solution of 3 (350 mg, 0.82 mmol, 1 equiv.) in methanol (3 mL), and the reaction mixture was stirred for 4 h in the open air. The clear solution was cooled down to room temperature and the solution was poured in another flask, freezed in liquid nitrogen and lyophilized to give a pure solid (white powder, 182.0 mg, 96% yield). -48.36 (c = 1.00 in H2O);1H NMR (400 MHz, D2O): = 4.17 – 3.96 (m, 1H), 2.17 – 1.85 (m, 2H), 1.74 – 1.42 (m, 2H), 0.98 – 0.61 (m, 2H).13C NMR (100 MHz, D2O): = 173.9, 53.0, 32.3, 16.6, 9.8;29Si NMR (119 MHz, D2O): = -38.83, -48.33, -58.08, 67.78; HRMS (ESI): m / z calcd for C5H14NO5Si: 196.0636 [M]+; found 196.0636. Synthesis of Silamate II General procedure for 4 To a suspension of (S)-methionine (20.0 g, 134 mmol, 1.0 equiv.) in methanol (250 mL) at 0 °C was added dropwise thionyl chloride (15 mL, 201 mmol, 1.5 equiv.). The reaction mixture was stirred at room temperature for 16 h. Volatiles were evaporated and the residue dried under high vacuum to afford to the desired compound 4 (white solid, 30.5 g, quantitative yield).1H NMR (300 MHz, DMSO-d6): =8.83 (s, 3H), 4.11 – 4.02 (m, 1H), 3.73 (s, 3H), 2.70 – 2.51 (m, 2H), 2.15 – 2.07 (m, 2H), 2.05 (s, 3H);13C NMR (100 MHz, DMSO-d6): =169.6, 52.8, 50.8, 29.3, 28.4, 14.2. These data are in agreement with those previously reported (A. Lumbroso, V. Coeffard, E. Le Grognec, I. Beaudet, J. P. Quintard, Tetrahedron Lett.2010, 51, 3226-3228). General procedure for 5 To a solution of 4 (16.6 g, 83.1 mmol, 1 equiv.) in a mixture tetrahydrofuran / water (160 mL, 1:1) at 0 °C were added sodium hydrogen carbonate (21.0 g, 250 mmol, 3 equiv.) then benzyl chloroformate (12.9 mL, 91.5 mmol, 1.1 equiv.). The reaction was allowed to slowly warm-up to room temperature and stirred for 16 h. The reaction was quenched with a saturated aqueous solution of ammonium chloride (150 mL). The aqueous layer was extracted with dichloromethane (3 x 150 mL). The combined organic layers were dried over magnesium sulfate, filtered and evaporated to dryness to afford to 5 (orange oil, 25.0 g, quantitative yield). The product was used such as without further purification.1H NMR (400 MHz, CDCl3): =7.38 – 7.29 (m, 5H), 5.43 (d,3JH-H= 6.3 Hz, 1H), 5.11 (s, 2H), 4.50 (q,3JH-H = 7.4 Hz, 1H), 3.75 (s, 3H), 2.53 (t,3JH-H = 7.3 Hz, 2H), 2.18 – 2.10 (m, 1H), 2.08 (s, 3H), 2.01 – 1.91 (m, 1H);13C NMR (100 MHz, CDCl3): =172.4, 155.8, 136.1, 128.3 (2C), 128.0, 127.9 (2C), 66.8, 53.0, 52.3, 31.6, 29.7, 15.2. These data are in agreement with those previously reported (A. Lumbroso, V. Coeffard, E. Le Grognec, I. Beaudet, J. P. Quintard, Tetrahedron Lett.2010, 51, 3226-3228). General procedure for 6 To a solution of 5 (17.0 g, 57.2 mmol, 1 equiv.) in methanol (120 mL) at 0 °C was added slowly a solution of sodium periodate (13.5 g, 62.9 mmol, 1.1 equiv.) in water (60 mL). The reaction was stirred at room temperature for 16 h. The suspension was filtered and the filtrate concentrated. The resulting aqueous solution was extracted with dichloromethane three times. The combined organic layers were washed with water, saturated aqueous of sodium chloride, dried over magnesium sulfate, filtered and evaporated to afford the corresponding compound 6 (slightly yellow oil, 17.915 g, quantitative yield).1H NMR (400 MHz, CDCl3): =7.39 – 7.28 (m, 5H), 5.95 – 5.78 (m, 1H), 5.09 (s, 2H), 4.50 – 4.43 (m, 1H), 3.74 (s, 3H), 2.80 – 2.64 (m, 2H), 2.52 (s, 3H), 2.40 – 2.31 (m, 1H), 2.18 – 2.07 (m, 1H);13C NMR (100 MHz, CDCl3): =171.7, 156.1, 136.1, 128.3 (2C), 128.0, 127.9 (2C), 66.8, 52.7, 49.9, 38.1, 25.2. These data are in agreement with those previously reported (A. Lumbroso, V. Coeffard, E. Le Grognec, I. Beaudet, J. P. Quintard, Tetrahedron Lett.2010, 51, 3226-3228). General procedure for 7 To 250 mL round-bottomed flask containing the sulfoxide compound 6 (10.00 g, 32.0 mmol, 1 equiv.) was introduced mesitylene (330 mL) at room temperature. The reaction was stirred at 175 °C for 48 h. After cooling to room temperature, the solvent was partially removed by distillation under pressure. The residue was purified two times by flash chromatography on silica gel (Tol / Et2O 90:10 then Petet / Et2O 80:20) to afford to the protected vinylglycine 7 (slightly yellow oil, 4.8 g, 60% yield). Rf=0.20 (Petet / Et2O 80:20);1H NMR (400 MHz, CDCl3): =7.40 – 7.29 (m, 5H), 5.98 – 5.84 (m, 1H), 5.58 – 5.44 (m, 1H, H2), 5.31 (dd, J = 17.1, 1.4 Hz, 2H, H1), 5.13 (s, 2H), 4.98 – 4.86 (m, 1H), 3.76 (s, 3H);13C NMR (100 MHz, CDCl3): =171.0, 155.7, 136.3, 132.4, 128.6 (2C), 128.3, 128.2 (2C), 117.9, 67.2, 56.2, 52.8. These data are in agreement with those previously reported (A. Lumbroso, V. Coeffard, E. Le Grognec, I. Beaudet, J. P. Quintard, Tetrahedron Lett.2010, 51, 3226-3228). General procedure for 8 To a solution of 7 (1.15 g, 4.61 mmol, 1 equiv.) in tetrahydrofuran (50 mL) at room temperature was added triethoxysilane (1.25 mL, 6.93 mmol, 1.5 equiv.) then Karstedt’s catalyst (Platinum(0)-1,3-divinyl-1,1,3,3- tetramethyldisiloxane complex, 2% platinum in xylenes, 0.53 mL, 0.046 mmol, 0.01 equiv.). The reaction mixture was stirred at 60 °C for 16 h, then evaporated. The black oil residue was purified by flash chromatography on silica gel leading to the desired compound 8 (slightly yellow oil, 1.18 g, 75% yield). Rf=0.31 (Tol / Et2O / Si(OCH3)49:1:0.05); [ ].= 10.68 (c = 1.00 in CHCl3);1H NMR (400 MHz, CDCl3): =7.38 – 7.28 (m, 5H), 5.47 (d,3JH-H = 7.2 Hz, 1H), 5.11 (s, 2H), 4.36 (q,3JH-H = 7.1 Hz, 1H), 3.79 (q,3JH-H = 7.0 Hz, 6H), 3.74 (s, 3H), 2.04 – 1.89 (m, 1H), 1.87 – 1.74 (m, 1H), 1.21 (t,3JH-H= 7.0 Hz, 9H), 0.70 – 0.51 (m, 2H);13C NMR (100 MHz, CDCl3): =172.8, 156.1, 136.5, 128.6 (2C), 128.3, 128.2 (2C), 67.1, 58.7 (3C), 55.8, 52.4, 26.1, 18.4 (3C), 5.9;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 3.79 / -46.51, 0.62 / -46.71; HRMS (APCI): m / z calcd for C19H31NO7SiH: 414.1943 [M+H]+; found 414.1932. General procedure for II To an aqueous hydrochloric solution (6N, 15 mL) at gentle reflux (115 °C) was added a solution of 7 (300 mg, 0.73 mmol, 1 equiv.) in methanol (1 mL), and the reaction mixture was stirred at reflux for 4 h in the open air. The clear solution was cooled down to room temperature, degassed by bubbling of argon and lyophilised to give a pure solid (white powder, 142.0 mg, 90% yield). M.p.70°C; [ ].= 15.49 (c = 1.00 in H2O);1H NMR (400 MHz, D2O): = 4.11 – 4.02 (m, 1H), 2.16 – 2.05 (m, 2H), 0.89 – 0.66 (m, 2H);13C NMR (100 MHz, D2O): =172.0, 54.7, 23.8, 7.1 (bs);29Si NMR (119 MHz, D2O): = -40.4, -49.7; HRMS (ESI): m / z calcd for C4H12NO5Si: 182.0479 [M+H]+; found 182.0480. Synthesis of Silamate II-15N General procedure for 4-15N To a suspension of (S)-methionine (5.0 g, 33.5 mmol, 1.0 equiv.) in methanol (62.5 mL) at 0 °C was added dropwise thionyl chloride (3.75 mL, 50.25 mmol, 1.5 equiv.). The reaction mixture was stirred at room temperature for 16 h. Volatiles were evaporated and the residue dried under high vacuum to afford to the desired compound 4-15N (white solid, 6.7 g, 100% yield). [ ].= 25.07 (c = 1.00 in MeOH) ;1H NMR (300 MHz, MeOD): = 4.24 (t,3JH-H = 6.3 Hz, 1H), 3.88 (s, 3H), 3.34 – 3.3 (m, 2H), 2.68 (t,3JH-H = 7.5 Hz, 2H), 2.14 (s, 3H);13C NMR (100 MHz, MeOD): =169.4, 52.4, 51.35 (d,1JC-N = 6.8 Hz), 29.2, 28.6, 13.5. HRMS (ESI): m / z calcd for C6H1315NO2SH: 165.0710 [M+H]+; found 165.0707. General procedure for 5-15N To a solution of 4-15N (4.15 g, 20.8 mmol, 1 equiv.) in a mixture tetrahydrofuran / water (40 mL, 1:1) at 0 °C were added sodium hydrogen carbonate (5.25 g, 62.5 mmol, 3 equiv.) then benzyl chloroformate (3.2 mL, 22.9 mmol, 1.1 equiv.). The reaction was allowed to slowly warm-up to room temperature and stirred for 16 h. The reaction was quenched with a saturated aqueous solution of ammonium chloride (38 mL). The aqueous layer was extracted with dichloromethane (3 x 38 mL). The combined organic layers were dried over magnesium sulfate, filtered and evaporated to dryness to afford to 5-15N (orange oil, 6.3 g, quantitative yield). The product was used such as without further purification. [ ].= 9.85 (c = 1.00 in CHCl3);1H NMR (400 MHz, CDCl3): =7.38 – 7.30 (m, 5H), 5.41 (dd,2JH-N = 91.2 Hz,3JH-H = 8.2 Hz, 1H), 5.11 (s, 2H), 4.50 (q,3JH-H = 7.1 Hz, 1H), 3.75 (s, 3H), 2.53 (t,3JH-H= 7.4 Hz, 2H), 2.26 – 2.11 (m, 1H), 2.08 (s, 3H), 2.00 – 1.89 (m, 1H);13C NMR (100 MHz, CDCl3): =172.5, 155.9 (d,1JC-N= 26.7 Hz), 136.2, 128.6 (2C), 128.3, 128.2 (2C), 67.1, 53.1 (d,1JC-N= 13.1 Hz), 52.6, 32.0, 29.9, 15.5. HRMS (ESI): m / z calcd for C14H1915NO4SH: 299.1078 [M+H]+; found 299.1078. General procedure for 6-15N To a solution of 5-15N (4.25 g, 14.3 mmol, 1 equiv.) in methanol (30 mL) at 0 °C was added slowly a solution of sodium periodate (3.4 g, 15.7 mmol, 1.1 equiv.) in water (15 mL). The reaction was stirred at room temperature for 16 h. The suspension was filtered and the filtrate concentrated. The resulting aqueous solution was extracted with dichloromethane three times. The combined organic layers were washed with water, saturated aqueous of sodium chloride, dried over magnesium sulfate, filtered and evaporated to afford the corresponding compound 6-15N (slightly yellow oil, 4.48 g, quantitative yield). [ ].= 16.13 (c = 1.00 in CHCl3) ;1H NMR (400 MHz, CDCl3): =7.39 – 7.30 (m, 5H), 5.68 (dd,2JH-N = 91.5 Hz,3JH-H = 8.0 Hz, 1H), 5.11 (s, 2H), 4.56 – 4.39 (m, 1H), 3.76 (s, 3H), 2.82 – 2.65 (m, 2H), 2.55 (s, 3H), 2.43 – 2.33 (m, 1H), 2.21 – 2.08 (m, 1H);13C NMR (100 MHz, CDCl3): =172.2, 156.5 (d,1JC-N = 25.5 Hz), 136.5, 129.0 (d,6JC-N= 1.8 Hz, 2C), 128.8 (d,5JC-N= 3.3 Hz, 2C), 67.8, 53.3, 50.6 (d,1JC-N= 12.9 Hz) , 39.0, 26.4. HRMS (ESI): m / z calcd for C14H1915NO5SH: 315.1027 [M+H]+; found 315.1028. General procedure for 7-15N To 100 mL round-bottomed flask containing the sulfoxide compound 6- 15N (2.50 g, 8.0 mmol, 1 equiv.) was introduced mesitylene (83 mL) at room temperature. The reaction was stirred at 175 °C for 48 h. After cooling to room temperature, the solvent was partially removed by distillation under pressure. The residue was purified two times by flash chromatography on silica gel (Tol / Et2O 90:10 then Petet / Et2O 80:20) to afford to the protected vinylglycine 7-15N (slightly yellow oil, 1.5 g, 73% yield). Rf=0.20 (Petet / Et2O 80:20); [ ].= 2.29 (c = 1.00 in CHCl3)1H NMR (400 MHz, CDCl3): =7.37 – 7.31 (m, 5H), 5.95 – 5.86 (m, 1H), 5.39 – 5.27 (m, 3H), 5.13 (s, 2H), 4.99 – 4.90 (m, 1H), 3.77 (s, 3H);13C NMR (100 MHz, CDCl3): =170.9, 155.5 (d,1JC-N = 27.2 Hz), 136.2, 132.3, 128.6 (2C), 128.3, 128.2 (2C), 117.9, 67.2, 56.2, 52.8. HRMS (ESI): m / z calcd for C13H1515NO4Na: 273.0864 [M+Na]+; found 273.0857. General procedure for 8-15N To a solution of 7-15N (1.15 g, 4.61 mmol, 1 equiv.) in tetrahydrofuran (50 mL) at room temperature was added triethoxysilane (1.25 mL, 6.93 mmol, 1.5 equiv.) then Karstedt’s catalyst (Platinum(0)-1,3-divinyl-1,1,3,3- tetramethyldisiloxane complex, 2% platinum in xylenes, 0.53 mL, 0.046 mmol, 0.01 equiv.). The reaction mixture was stirred at 60 °C for 16 h, then evaporated. The black oil residue was purified by flash chromatography on silica gel leading to the desired compound (slightly yellow oil, 1.28 g, 81% yield). Rf=0.31 (Tol / Et2O / Si(OCH3)49:1:0.05); [ ].= 5.33 (c = 1.00 in CHCl3);1H NMR (400 MHz, CDCl3): =7.41 – 7.28 (m, 5H), 5.54 (dd,2JH-N = 91.5 Hz,3JH-H = 8.3 Hz, 1H), 5.26 – 4.91 (m, 2H), 4.35 (q,3JH-H = 7.0 Hz, 1H), 3.78 (q,3JH-H = 7.0 Hz, 6H), 3.71 (s, 3H), 2.11 – 1.87 (m, 1H), 1.87 – 1.65 (m, 1H), 1.19 (t,3JH-H = 7.0 Hz, 9H), 0.67 – 0.52 (m, 2H);13C NMR (100 MHz, CDCl3): =172.8, 156.0 (d,1JC-N = 26.7 Hz), 136.4, 128.5 (2C), 128.14, 128.10 (2C), 66.9, 58.5 (3C), 55.7 (d,1JC-N = 13.1 Hz), 52.3, 26.0, 18.3 (3C), 5.8;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 3.80 / -46.56, 0.55 / -46.56; HRMS (ESI): m / z calcd for C19H3115NO7Na: 437.1732 [M+Na]+; found 437.1732. General procedure II-15N To an aqueous hydrochloric solution (6N, 5 mL) at gentle reflux (115 °C) was added a solution of 8-15N (100 mg, 0.24 mmol, 1 equiv.) in methanol (0,3 mL), and the reaction mixture was stirred at reflux for 4 h in the open air. The clear solution was cooled down to room temperature, degassed by bubbling of argon and lyophilised to give a pure solid (white powder, 47.3 mg, 90% yield). M.p.79°C; [ ].= 154.70 (c = 0.40 in H2O);1H NMR (400 MHz, D2O): = 3.97 – 3.93 (m, 1H), 2.05 – 1.99 (m, 2H), 0.78 – 0.61 (m, 2H);13C NMR (100 MHz, D2O): =171.6, 54.5, 23.7, 7.4 (bs);29Si NMR (119 MHz, D2O): = -40.28, -49.67; HRMS (ESI): m / z calcd for C4H1215NO5SiH: 183.0450 [M+H]+; found 183.0450. Synthesis of Silartate III General procedure for triallyl(chloromethyl)silane 9 To a solution of (chloromethyl)trichlorosilane (1.40 mL, 11.2 mmol) in diethyl ether (100 mL) at 0 °C was added slowly a solution of allylmagnesium chloride (1.7 M in tetrahydrofuran, 22 mL, 37.0 mmol). After the addition, the reaction was stirred at room temperature for 2 h. The reaction was quenched with a saturated aqueous solution of ammonium chloride (100 mL) and the aqueous layer was extracted with diethyl ether (2 x 100 mL). The combined organic layers were washed with a saturated aqueous solution of sodium chloride (100 mL), dried over magnesium sulphate, filtered and evaporated to dryness. The residue was purified by filtration over a pad of silica gel (eluent: petroleum ether) to afford to the expected compound (colorless oil, 1.96 g, 87% yield).1H NMR (400 MHz, CDCl3): =5.79 (ddt,3JH-H = 17.0, 10.1, 8.1 Hz, 3H), 4.99 – 4.90 (m, 6H), 2.85 (s, 2H), 1.72 (dt,3JH-H= 8.1, 1.2 Hz, 6H);13C NMR (100 MHz, CDCl3): =133.1 (3C), 114.8 (3C), 26.6, 18.1 (3C). These data are in agreement with those previously reported;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 2.89 / -1.17, 1.72 / -0.98 (E. S. Finkel'shtein, E. B. Portnykh, N. V. Ushakov, V. M. Vdovin, Russ Chem Bull.1981, 30, 483-487). General procedure for triallyl(iodomethyl)silane 10 To a solution of 9 (790 mg, 3.93 mmol) in acetonitrile (40 mL) at room temperature was added sodium iodide (1.47 g, 9.84 mmol, 2.5 equiv.). The reaction mixture was stirred at 80 °C for 16 h. The reaction was cooled down to room temperature and poured into water (200 mL). The aqueous layer was extracted with a mixture of diethyl ether and petroleum ether (1:4, 2 x 100 mL). The combined organic layers were washed with a satured aqueous solution of sodium chloride (50 mL), dried over magnesium sulfate, filtered and evaporated under pressure. The residue was purified by filtration over a pad of silica gel (eluent: petroleum ether) to afford to the compound (colorless oil, 1.123 g, 98% yield).1H NMR (400 MHz, CDCl3): =5.79 (ddt,3JH-H = 17.0, 10.1, 8.1 Hz, 3H), 5.02 – 4.89 (m, 6H), 2.04 (s, 2H), 1.74 (dt,3JH-H= 8.1, 1.1 Hz, 6H);13C NMR (100 MHz, CDCl3): =133.1 (3C), 114.6 (3C), 19.1 (3C);1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 2.03 / -0.39, 1.73 / -0.41; HRMS (APCI): m / z calcd for C10H17IsiH: 293.0217 [M+H]+; found 293.0216 General procedure for N-(diphenylmethylene)glycine tert-butyl ester 11 A mixture of glycine tert-butyl ester hydrochloride (3.00 g, 17.9 mmol, 1 equiv.) and benzophenone imine (3.24 g, 17.9 mmol, 1 equiv.) in 15 suspension in dichloromethane (200 mL, 0.1 M) was stirred at room temperature for 16 h. The volatiles were removed under vacuum and the residue was taken with a mixture of diethyl ether (50 mL) and dichloromethane (25 mL) and washed succesvely with water (25 mL), saturated aqueous sodium hydrogen carbonate solution (25 mL), saturated aqueous sodium chloride (25 mL). After evaporation under pressure, the solid was dissolved in a minimum volume of DCM. When hexane was slowly added to the resulting solution cooled at 0 °C, a solid was formed. The pure solid was collected by filtration (white solid, 4.932 g, 93% yield).1H NMR (400 MHz, CDCl3): =7.66 (d,3JH-H = 7.8 Hz, 2H), 7.50 – 7.43 (m, 3H), 7.43 – 7.36 (m, 1H), 7.36 – 7.30 (m, 2H), 7.21 – 7.16 (m, 2H), 4.12 (s, 2H), 1.46 (s, 9H);13C NMR (100 MHz, CDCl3): =171.6, 170.0, 139.6, 136.3, 130.5, 128.9, 128.7, 128.2, 127.9, 81.2, 56.5, 28.3.These data are in agreement with those previously reported (P. Nun, V. Perez, M. Calmes, J. Martinez, F. Lamaty, Chemistry.2012, 18, 3773-3779). General procedure for tert-butyl 2-((diphenylmethylene)amino)-3-(triallylsilyl)propanoate 12 To a solution of diisopropylamine (0.85 mL, 6.09 mmol, 1.2 equiv.) in tetrahydrofuran (15 mL) equiv.) in tetrahydrofuran (15 mL) at 0 °C. The mixture was stirred at 0 °C for 30 min then added to a solution of 10 (1.78 g, 6.10 mmol, 1.2 equiv.) in tetrahydrofuran (15 mL) at 0 °C. The reaction mixture was allowed to slowly warm-up to room temperature and stirred for 16 h. The reaction was quenched with a saturated aqueous ammonium chloride solution (100 mL) and the aqueous layer was extracted with diethyl ether (2 x 50 mL). The combined organic layers were washed with a saturated aqueous sodium chloride solution (50 mL), dried over magnesium sulfate, filtered and evaporated to dryness to afford to an orange oil. The crude material was purified by flash chromatogaphy on silica gel to afford to the expected compound 12 (colorless oil, 2.16 g, 93% yield). Rf=0.33 (Petet / Et2O 9.5:0.5);1H NMR (300 MHz, CDCl3): =7.68 – 7.63 (m, 2H), 7.48 – 7.42 (m, 3H), 7.40 – 7.29 (m, 3H), 7.21 – 7.16 (m, 2H), 5.82 – 5.65 (m, 3H), 4.85 – 4.75 (m, 6H), 4.11 (t,3JH-H = 6.7 Hz, 1H), 1.57 (d,3JH-H = 8.1 Hz, 6H), 1.44 (s, 9H), 1.35 (dd,3JH-H = 14.7, 7.0 Hz, 1H), 1.21 (dd,3JH-H = 14.7, 6.4 Hz, 1H);13C NMR (100 MHz, CDCl3): =172.3, 168.9, 139.5, 136.6, 134.5 (3C), 130.3, 128.9 (2C), 128.7, 128.6 (2C), 128.1 (2C), 127.9 (2C), 113.8 (3C), 81.0, 62.8, 28.2 (3C), 20.3 (3C), 16.7;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 4.12 / -1.48, 1.57 / -1.48, 1.29 / -1.37; HRMS (ESI): m / z calcd for C29H37NO2SiH: 460.2666 [M+H]+; found 460.2672. General procedure for tert-butyl 2-amino-3-(triallylsilyl)propanoate 13 To a solution of 12 (1.86 g, 4.05 mmol, 1.0 equiv.) in tetrahydrofuran (25 mL) at room temperature was added a solution of citric acid (3.89 g, 20.2 mmol, 5.0 equiv.) in water (25 mL). The reaction mixture was stirred at room temperature for 16 h. The reaction was quenched with a saturated aqueous sodium hydrogen carbonate solution (50 mL) and the aqueous layer was extracted with dichloromethane (4 x 25 mL). The combined organic layer were dried over magnesium sulfate, filtered and evaporated to afford to a colorless oil. The crude material was purified by flash chromatography on silica gel to afford to the desired compound 13 (colorless oil, 1.034 g, 86% yield). Rf=0.24 (Petet / EtOAc 9:1);1H NMR (400 MHz, CDCl3): =5.82 (dq,3JH-H= 17.1, 8.8 Hz, 3H), 4.96 – 4.85 (m, 6H), 3.37 (dd, J = 10.4, 4.5 Hz, 1H), 1.69 (d,3JH-H = 8.1 Hz, 6H), 1.46 (s, 9H), 1.41 (br, 2H), 1.10 (dd,3JH-H= 14.9, 4.5 Hz, 1H), 0.82 (dd,3JH-H= 14.8, 10.5 Hz, 1H);13C NMR (100 MHz, CDCl3): =176.9, 134.5 (3C), 114.0 (3C), 80.9, 52.2, 28.2 (3C), 20.3 (3C), 17.9;1H / 29Si-HMQC NMR (300 / 60 MHz, CDCl3): = 1.69 / -1.14, 1.10 / -1.16, 0.82 / -1.09; HRMS (ESI): m / z calcd for C16H29NO2SiH: 296.2040 [M+H]+; found 296.2045. General procedure for 2-amino-3-(trihydroxysilyl)propanoic acid hydrochloride III To an aqueous hydrochloric acid 6N solution was added 13 (100 mg, 0.34 mmol, 1.0 equiv.) and the reaction mixture was stirred open-air at gentle reflux for 1 h. The reaction was cooled down to room temperature and degassed by bubbling of argon. The solution was transferred into vial and freeze-dried to afford to the title compound (white solid, 56 mg, 75% yield). M.p.95°C;1H NMR (400 MHz, D2O): =4.30 – 4.09 (m, 1H), 1.57 – 1.23 (m, 2H);13C NMR (100 MHz, D2O): =171.9, 49.8, 15.2;29Si NMR (119 MHz, D2O): = -45.44, -54.82; HRMS (ESI): m / z calcd for C3H10NO5Si: 168.0323 [M]+; found 168.0326. Diffusion coefficient measurements. The self-diffusion coefficient of the silanetriol acid II (11 mM) solutions in D2O at 295 K at t=0 and t=16 days were determined by the PGSE-NMR technique (Stejskal, E. O.; Tanner, J. E. J. Chem. Phys., 1965, 42, 288-92)., by monitoring the1H signal on a Bruker Avance 500 spectrometer equipped with a field gradient probe unit. The ledbpgp2s 2D sequence combining constant time, bipolar pulse, stimulated echo, and the longitudinal eddy current delay method, was used (Wu, D. ; Chen, A. ; Johnson Jr, C.S. J. Magn. Reson. A, 1995, 115, 260-264). All the NMR signals give rise to monoexponential decays following A = A exp[- H² ²G²( – / 3) D] where A is the echo amplitude in the presence of the gradient pulse, A0 is the echo amplitude in the absence of the gradient pulse, H is the proton gyromagnetic ratio, is the gradient pulse length, G is the strength of the applied field gradient, is the interval between two field gradient pulses, and D is the diffusion coefficient. By varying the field gradient amplitude G, a series of experiments was collected, and the diffusion coefficient was extracted using a simple fit to eq 1 for the three aliphatic peaks. From DOSY recorded with the sample of II just prepared (t=0, Fig. 6), the averaged diffusion coefficient is equal to 1.056x10-10 m² / s, while from DOSY recorded with the same sample after letting it evolve for 16 days (Fig.7) results in an averaged diffusion coefficient equal to 4.137x10-10 m² / s. The factor four is clearly indicative of a depolymerization pathway from an oligomeric structure to the free silanetriol acid. Transamination reactions between silanetriol amino acids (I-III) and the oxoglutarate a) Triethanolamine buffer solution preparation To a 30 mL beaker equipped with a magnetic stirrer, HPLC grade water (10.0 mL), triethanolamine (0,250 g), PLP (4 mg) were added. Under gentle stirring at rt, concentrated HCl was added dropwise. After pH reached 7.5 (indicated by a pH meter), the total volume was then adjusted to 15.0 mL by adding HPLC grade water. The buffer solution was used directly for transamination. b) General procedures for transamination To a 5 mL vial equipped with a magnetic stir bar was added the Silanetriol amino acid (0.01 mmol) and the oxoglutarate (1.46 mg, 0.01 mmol). Triethanolamine buffer at pH = 7.5 (1.0 mL) was then added. Transaminase (1.0 mg) were then added sequentially. The reaction vial was capped by a screw cap and stirred vigorously (1000 rpm) at 37oC for 24 h. After 24h, the reaction was then filtered by a PTFE membrane 0.2 m and directly analysed by ultrahigh- resolution mass spectrometry. Solutions of (30 µg / mL, H2O) were injected using a syringe pump (300 µL / h) into the electrospray ionization source (negative mode) of a 7 T hybrid quadrupole-FT-ICR mass spectrometer (SolariX XR h-Q-h, Bruker Daltonics, Billerica, USA). A mass resolving power of 3 x 105at m / z 150 was used. The average scan number was set at 500 with 1 second accumulation time. The temperature of the source was set at 280 °C, the ESI voltage at 3900 V, the capillary exit at -220 V, the skimmer I at -10 V, the skimmer II at -4 V and the hexapole collision voltage at -1 V. Example 1: Synthesis of silanetriol amino acids The inventors contemplated two reaction classes to forge the key carbon-silicon bonds of silanetriol amino acids I-III. The first consisted of the transition metal-catalyzed hydrosilylation, the second of the alkylation of a glycyl anion by a silyl electrophile (sila- alkylation). An inherent difficulty in such synthetic routes is to introduce the required functional groups in the appropriate order, relying on masked silanetriol groups to be eventually deprotected. Given the ready availability of allylglycine, the synthesis of Silamipate I by hydrosilylation was first attempted (Scheme 1a). L-allylglycine was quantitatively esterified using thionyl chloride in methanol to give 1, followed by amino group protection as benzyl carbamate (2, 91%). Several catalytic systems for the key hydrosilylation step were comparatively tried, the platinum-based Karstedt catalyst giving the best yield of the triethoxysilyl compound 3 (up to 70%). One-pot triple deprotection (triethoxysilane, N-carbamate, methyl ester) was performed with excellent yield by acid hydrolysis with 6N HCl. After freeze-drying, the target molecule I was obtained with an excellent yield of 85%. A similar route was followed to synthesize Silamate II (Scheme 1a). Vinylglycine intermediate 7 was prepared in four steps from L-methionine according to the literature (Tetrahedron Letters 2010, 51, 3226–3228). After protection of the amino and carboxyl groups (5), oxidation of sulfur using sodium periodate yielded the corresponding sulfoxide 6. Thermal elimination of sulfenic acid in mesitylene gave the desired precursor 7 in 60% yield, which needed thorough purification prior to the hydrosilylation step. The latter proceeded smoothly to give 8 with a yield of 73%, accompanied in some reactions by the hydrogenation product (maximum 5%). In that case, careful separation of the two compounds by column chromatography was carried out, to avoid contamination of II by the amino acid norvaline. Finally, a triple deprotection as above gave the expected Silamate II with an excellent yield of 90%. The same reaction sequence was applied to the commercially available15N-labeled L- methionine and afforded the corresponding15N-Silamate with comparable yield (materials and methods). The hydrosilylation reaction was also considered to prepare Silartate III. Thus, easily accessible protected dehydroalanine was engaged in the previous conditions but no silylated adduct was formed. Alkylation of Schiff base derivatives of glycine by the O'Donnell method seemed worth exploring (Tetrahedron Letters 1978, 19, 2641–2644). Triallyl(iodomethyl)silane 10, obtained by the Finkelstein reaction on the corresponding chloride 9 (Russ. Chem. Bull.1981, 30, 483–487), was assayed as an electrophile bearing a masked silanetriol function. Indeed, triallylsilanes are known to convert into silanetriols through acid treatment (Chem. Sci.2017, 8, 416-422). The alkylation of the Schiff base 11 with 10 went smoothly. Hydrolysis with citric acid provided the free amine 13, and then with 6N HCl, in just one hour, the expected Silartate III in racemic form in 75% yield (Scheme 1b). Example 2: Structural and biochemical analysis of silanetriol amino acids These syntheses could be scaled up to gram quantities. This made it possible to conduct structural as well as biochemical studies. Focusing on Silamate II, the inventors investigated the effect of pH (<2 and >11) duration (0, 8 and 17 days) and concentration (0.01 to 0.22 M) on condensation processes by the silanetriol group (see SI). Multinuclear NMR studies were carried out.13C and29Si NMR spectra were found highly informative to this end, demonstrating the formation of siloxane crosslinks upon increasing concentration but without significant influence of pH and time. In accordance with the literature (J. Organometal. Chem.2001, 625, 208–216),29Si NMR shifts allowed to distinguish free silane triols, mono-crosslinked (M), di- crosslinked (D) and tri-crosslinked (T) structures (Figure 2). In parallel,1H NMR spectra and DOSY experiments at c = 0.01 M revealed the evolving spectral resolution from poorly- resolved signals for just-prepared samples to well-resolved resonances after some hours or days. This is highly suggestive of depolymerisation of siloxane networks liberating monomer II as already observed by Sieburth (J. Org. Chem.2012, 77, 2901–2906). The inventors then investigated the interaction of the new-to-nature amino acids with a biocatalyst. The three compounds I-III were engaged in transamination reactions using 2- oxoglutarate as a co-substrate and a commercial aminotransferase as a catalyst and pyridoxal 5'-phosphate (PLP) as co-catalyst (Scheme 2). The enzyme (according to the vendor Sigma Aldrich) is of bacterial origin and shows an elevated activity in converting oxoglutarate to L- glutamate using a wide spectrum of L-amino acids. Application of the enzymatic assay to the three silanetriol amino acids I-III resulted in the formation of a product chromatographically indistinguishable from glutamate (as detected by ninhydrin after TLC). MS analysis corroborated these observations by showing the formation of an entity with the mass of glutamate and also, except in the reaction of III, of entities whose masses corresponded to silanetriol oxo acids in the proportions expected for the natural isotopes of silicon (28Si,29Si, and30Si). Subjected to the same enzymatic assay,15N-L-silamate led to the appearance of an entity with the mass expected for15N-L-glutamate. Altogether, the enzymatic results established that the three silanetriol amino acids which were synthesized undergo enzymatic transamination and that spontaneous condensation reactions into siloxanes (including silanetriol oxo acid products) do not thwart biocatalysis. Example 3: Utilization of the silanetriol amino acid Silaglutamate as a nitrogen source by two species of Proteobacteria Silaglutamate (also designated as Silamate), as shown below, is the S enantiomer of the compound (HO)3Si-CH2-CH2-CH(NH2)-CO-OH. It corresponds to the substitution of the lateral carboxylic group (CO2H) of glutamate with silanetriol (Si(OH)3. Two reference bacterial strains were used, ADP1 for Acinetobacter baylyi and KT2440 for Pseudomonas putida. The same defined culture medium, designated MSN, was used for all species, the composition of which was as follows: Na gluconate: 10 millimolar; citric acid: 4 millimolar; MgSO4: 1 millimolar; K2HPO4: 50 millimolar; nitrilotriacetic acid: 10 micromolar; CaCl2: 3 micromolar; FeCl3: 3 micromolar; MnCl2: 1 micromolar; ZnCl2: 0.1 micromolar; CoCl2: 0.1 micromolar; NiCl2: 0.1 micromolar; CrCl3: 0.1 micromolar; CuCl2: 0.1 micromolar; Na2MoO4: 0.1 micromolar; Na2SeO3: 0.1 micromolar. A nitrogen source was added at a concentration of 10 millimolar, composed of either NH4Cl, Glutamate (L) or Silaglutamate (L). The final pH reached 7.3. Agar at a concentration of 15 g / L was added to prepare solid medium plates. Acinetobacter baylyi and Pseudomonas putida were able to partially utilize this silanetriol amino acid. These results are shown in Figure 12. Serial culture by reinoculation at one-hundredth dilution in MSN Silaglutamate medium gave rise to an improvement in growth, for each of the two species Acinetobacter baylyi and Pseudomonas putida. These results are shown in Figure 13. Example 4: Incorporation of silaspartate by a reprogrammed strain of Escherichia coli in the outer membrane protein OmpC and immobilisation of cells of the reprogrammed strain in silica gel Silaspartate, as shown below, is the S enantiomer of the compound (HO)3Si-CH2-CH(NH2)-CO- OH. It corresponds to the substitution of the lateral carboxylic group (CO2H) of aspartate with silanetriol (Si(OH)3. General methods and procedures Procedures for PCR amplification, ligation and bacterial transformation are well known in the art. Cloning techniques suitable for use in the following examples may be found in Sambrook J., et al., Molecular Cloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor, N.Y., 1989. Materials and methods suitable for the maintenance and growth of bacterial cultures are well known in the art. Culture techniques suitable for use in the following examples may be found in Manual of Methods for General Bacteriology (Philipp Gerhardt, R.G.E. Murray, Ralph N. Costilow, Eugene W. Nester, Willis A. Wood, Noel R. Krieg and G. Briggs Philips, eds). All reagents and materials used for the growth and maintenance of bacterial cells are obtained from Sigma Aldrich Company (St. Louis. MO) unless otherwise specified. All cloning steps were performed in TOP10 E. coli (Thermo Fisher Scientific). The protein expression experiments were carried out with BL21 (DE3) (Lucigen, Middleton, WI). Plasmid construction This section describes the construction of a two plasmids system that allows the incorporation of the non-canonical amino acid Silaspartate in response to the amber codon into the OmpC protein expressed in a reprogrammed E. coli strain. The construction begins with the plasmid pTECH-MmPylRS(IPYE) (Addgene plasmid #104073) which contains the pylS pylT genes specifying the PylRS tRNAPyl orthogonal translation system and a chloramphenicol resistance gene. The MmPylRS(IPYE) gene is replaced with a pylS* gene encoding MaPylRSIFGFF by standard cloning techniques. The latter is a pyrrolysyl-tRNA synthetase (PylRS) variant from Methanomethylophilus alvus carrying the following mutations: L125I, Y126F, M129G, V168F, and Y206F. This variant is active toward a range of histidine analogues (https: / / onlinelibrary.wiley.com / doi / full / 10.1002 / pro.4640). The PylRSIFGFF gene is under the control of a very strong constitutive lpp promoter. The tRNAPyl gene pylT is under the control of the proK promoter. The final constructed plasmid is called pTECH-MaPylRSIFGFF. The plasmid pET28-OmpC-Y232TAG is constructed by cloning the ompC gene from E. coli into the widely used pET system containing a kanamycin resistance gene. The OmpC gene is first amplified by PCR from E. coli genome and then cloned into linearized pET28 backbone using Gibson Assembly (NEBuilder® HiFi DNA AssemblyMaster Mix, New England Biolabs). The amber stop codon (TAG) is introduced in the ompC gene at the position corresponding to Y232, by using the Q5TM Site-Directed Mutagenesis Kit (New England Biolabs). The Y232 mutation site corresponds to an exposed location in one of the eight external loops of OmpC (Spicer CD, Triemer T, Davis BG. Palladium-mediated cell-surface labeling. J Am Chem Soc. 2012 Jan 18;134(2):800-3). The expression of OmpC-Y322TAG is controlled by an IPTG inducible T7 promoter. Protein expression Incorporation of Silaspartate in response to the amber codon UAG is OmpC-Y232TAG using the engineered Pyl / tRNACUAPyl system. Cells of an E. coli strain bearing a chromosomal deletion of the ompC gene, BL21(DE3) ompC, are co-transformed with the two plasmids pET28-OmpC-Y232TAG and pTECH-MaPylRSIFGFF. The gene deletion is done following a procedure well known in the art (Datsenko KA.; Wanner BL. Proceedings of the National Academy of Sciences, 2000, vol.97 (12), 6640-6645). Protein expression is carried out in either minimal media or rich media supplemented with the required antibiotics kanamycin (50 g / mL) and chloramphenicol (37 g / mL), the inducer IPTG (0.1-1 mM), and in the presence or absence of Silaspartate (3 mM). Cultures are incubated with shaking at 37 °C for 16 h, and then 150 µL are taken and analysed by SDS-PAGE. Co-expression of the required Pyl / tRNACUAPyl translation system on the pTECH- MaPylRSIFGFF plasmid and OmpC-Y232TAG on the pET28 vector leads to the production of the OmpC protein only in presence of Silaspartate, as assessed on SDS-PAGE gels. E. coli cell immobilisation on silica gel The purpose of this section is to describe the incorporation of Silaspartate into the extracellular domain of the outer membrane porin C protein (OmpC) of E. coli and its effect. The presence of Silaspartate residues on the cells surface is exploited for immobilizing E. coli cells on silica gel. Sol–gel synthesis of silica is based on the strong tendency of orthosilicic or silicic acid to the condensation reaction: (OH)3Si-OH + HO-Si(OH)3(OH)3Si-O-Si(OH)3+ H2O, (1) as a result of which siloxane bridges Si-O-Si are formed. The two silicon atoms are bonded covalently to each other via oxygen. The remaining three silanol groups Si-OH at each silicon atom can in turn participate in further condensation reactions with (OH)3Si-OH + (OH)3Si-O-Si(OH)3+ HO-Si(OH)3(OH)3Si-O-Si(OH)2-O-Si(OH)2-O-Si(OH)3 + H2O, (2) which lead to polymerization and the formation of polysilicic acids. At the initial stage, oligomeric reaction products form sol particles. Their flocculation, which promotes the formation of covalent siloxane bonds between them, leads to a sol–gel transition with the formation of a three-dimensional network structure. The silanetriol group of Silaspartate (R-CH2-(OH)2Si-OH), as incorporated in the OmpC protein and displayed at the surface of E. coli cells, can substitute for silicic acid in condensation reactions at any stage and thereby covalently bond bacteria to the polysilicic sol-gel through siloxane bridges: R-CH2-(OH)2Si-OH + (OH)3Si-O-Si(OH)3 + HO-Si(OH)3 R-CH2-(OH)2Si-O-Si(OH)2-O-Si(OH)2-O-Si(OH)3 + H2O (3) E. coli BL21(DE3) ompC cells co-transformed with pET28-OmpC-Y232TAG and pTECH- MaPylRSIFGFF are grown in LB medium containing kanamycin (50 g / mL) and chloramphenicol (37 g / mL). When cultures are at their exponential growth state, the OmpC expression is triggered by adding 3 mM Silaspartate and 1 mM IPTG, and cell growth is continued at 37 °C with shaking for 16 h. Then 1 mL of culture is collected by centrifugation at 10,000 rpm for 20 min and washed with 1 ml of sterile PBS (pH 7.4). The washed cells are resuspended in a water–glycerol (10 wt%) phosphate buffer solution (cells 109ml1). The formation of silica gels encapsulating the E. coli cells is initiated by means of acidification down to pH 7. The mixture is homogenized under mild stirring. Gelation occurs within about 2 min at room temperature. Wet gels and aqueous bacteria suspensions are kept in their mother solution and aged in a closed flask at 20 °C. Aged gels are then dispersed in a phosphate buffer solution and washed to remove non-immobilised cells. Transmission electron micrographs show that the cellular integrity of bacteria is maintained within the gel.

Claims

New PCT-Patent Application Based on EP 23315348.5 Scientist of Fortune S.A. Vossius Ref.: AG2918 PCT BS CLAIMS 1. An amino acid according to formula (I):or its salt, wherein: Z is C0-6 alkylene, and / or X and Y are each independently hydrogen, -CN, C1-4 alkyl, -OH, -O(C1-4 alkyl), -(C1-4 alkylene)-OH, -SH, -S(C1-4 alkyl), -(C1-4 alkylene)-SH, -NH2, -NH(C1-4 alkyl) or -N(C1-4 alkyl)(C1-4 alkyl).

2. The amino acid according to claim 1, wherein the amino acid is according to formula (Ia): ,wherein n is an integer ranging from 1 to 7, preferably from 1 to 5, more preferably from 1 to 3, or its salt, preferably wherein the amino acid of formula (Ia) is an amino acid of formula (Ib):or its salt.

3. A polypeptide comprising the amino acid according to claim 1 or 2.

4. The polypeptide according to claim 3, wherein the polypeptide is immobilized on a solid by means of a siloxane bond.

5. The polypeptide according to claim 4, wherein the solid is a surface or a particle.

6. The polypeptide according to claim 4 or 5, wherein the solid comprises a functional group that allows for the formation of the siloxane bond.

7. The polypeptide according to claim 6, wherein the functional group that allows for the formation of the siloxane bond is comprised in a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, or a phosphate salt of phosphoric acid.

8. The polypeptide according to any one of claims 4 to 7, wherein the solid comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays.

9. The polypeptide according to any one of claims 3 to 8, wherein the polypeptide is an enzyme.

10. The polypeptide according to any one of claims 3 to 9, wherein the polypeptide is displayed on the surface of a cell, in particular a microbial cell.

11. The polypeptide according to any one of claims 3 to 8, wherein the polypeptide iscomprised in a virus particle, in particular in the capsid of a virus particle.

12. A siloxane (Si-O) cluster comprising the amino acid according to claim 1 or 2 and / or the polypeptide according to any one of claims 3 to 11.

13. The siloxane (Si-O) cluster according to claim 12, wherein the siloxane cluster comprises at least one siloxane bond, in particular wherein the siloxane bond comprises the structure (Si-O-Si), (Si-O-B) or (Si-O-P).

14. A solid surface or particle covalently linked to the amino acid according to claim 1 or 2 or the polypeptide according to any one of claims 3 to 11, wherein the amino acid or the polypeptide is covalently linked to the surface or the particle via a siloxane bond, in particular wherein the siloxane bond comprises the structure (Si-O-Si), (Si-O-B) or (Si-O- P).

15. The solid surface or particle according to claim 14, wherein the surface or particle comprises a molecule selected from the group consisting of: a silanol, a silanediol, a silanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, and a phosphate salt of phosphoric acid.

16. The solid surface or particle according to claim 14 or 15, wherein the surface or particle comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays.

17. An aminoacylated tRNA comprising the amino acid according to claim 1 or 2.

18. A method for obtaining an amino acid of claim 2, wherein n is an integer ranging from 2 to 7, the method comprising the step of reacting the compound of formula (II):(II) with HSi(OR)3in the presence of a Karstedt catalyst, wherein PG1and PG2are protecting groups for -NH2and -COOH groups, respectively, and each R is independently of each other selected from C1-6alkyl. Wherein the method further comprises the step(s) of deprotecting -Si(OH)3, -NH2and - COOH groups in the obtained product.

19. The method of claim 18, wherein PG1 is Cbz group, PG2 is C1-6 alkyl, and / or each R is ethyl.

20. A method for obtaining an amino acid of claim 1 or 2, the method comprising the step of reacting LG-Z-CXY-Si(OR)3, with PGN-CH2-COO-PG2 pretreated with a base capable of generating PGN-CH--COO-PG2 carbanion, wherein Z, X and Y are as defined in claim 1, LG is a leaving group, PGN is a protected -NH2 group, PG2 is a protecting group for -COOH group, and each R is independently of each other selected from C1-6 alkyl and C2-6 alkenyl, wherein the method further comprises the step(s) of deprotecting Si(OH)3, -NH2 and - COOH groups in the obtained product.

21. The method of claim 20, wherein n is 1, LG is iodo, PGN is (phenyl)2C=N-, PG2 is C1-6 alkyl, and / or each R is allyl.

22. A method of producing a polypeptide comprising a silanetriol amino acid at a specified position in a cell, the method comprising:a) growing, in an appropriate medium, the cell, wherein the cell comprises a nucleic acid that encodes the polypeptide, and wherein the nucleic acid comprises at least one selector codon; and b) providing the amino acid according to claim 1 or 2; wherein the cell further comprises: c) a nucleic acid sequence encoding an orthogonal aminoacyl-tRNA synthetase (O-RS), and, d) an orthogonal tRNA (O-tRNA), that recognizes the selector codon, wherein said O—RS aminoacylates the O-tRNA with the amino acid according to claim 1 or 2.

23. The method according to claim 22, wherein the selector codon is a nonsense codon, in particular an amber stop codon.

24. A method of immobilizing a polypeptide on a solid, the method comprising the steps of: a) providing a solid comprising a functional group that allows for the formation of a siloxane bond; b) contacting the solid of step (a) with the polypeptide according to any one of claims 3 to 11; c) immobilizing the polypeptide on the solid.

25. A method of equipping a solid with a biological agent, the method comprising the steps of: a) providing a solid comprising a functional group that allows for the formation of a siloxane bond; b) equipping the solid with a biological agent by contacting the solid of step (a) with the amino acid according to claim 1 or 2 or the polypeptide according to any one of claims 3 to 11.

26. The method according to claim 24 or 25, wherein the solid is a surface or a particle.

27. The method according to any one of claims 24 to 26, wherein the functional group that allows for the formation of a siloxane bond is comprised in a silanol, a silanediol, asilanetriol, a silicic acid, a silicate salt, a boric acid, a borate salt, or a phosphate salt of phosphoric acid.

28. The method according to any one of claims 24 to 27, wherein the solid comprises or consists of glass, silica, concrete, ceramics, zeolites, and / or clays.

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