1101 results about "Serine" patented technology

The invention relates to the field of gene engineering, and discloses a D-3-phosphoglycerate dehydrogenase mutant, a coding gene thereof and application of the D-3-phosphoglycerate dehydrogenase mutant and the coding gene. Compared with a protein with an amino acid sequence as shown in SEQ ID NO: 1, the mutant comprises mutation at the 131 site and / or the 285 site. The mutant can specifically catalyze a substrate 3-phosphoglycerate to synthesize 3-phosphate-hydroxypyruvic acid, can effectively promote synthesis of L-serine in a metabolic pathway of microorganisms, improves the yield and conversion rate of the L-serine, and reduces the yield of byproducts at the same time.

The invention discloses a high-performance carbonyl reductase mutant and application thereof in synthesis of a series of chiral alcohols. The high-performance carbonyl reductase mutant is obtained by performing the following mutations on an amino acid sequence as shown in SEQ ID NO.2: the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine, and the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine; and / or the 100th glycine is mutated into any one of glutamic acid, serine, lysine or asparagine. Compared with a wild type enzyme, the thermal stability and the catalytic activity of the obtained mutant are remarkably improved, particularly, single point mutants Mut-A69N, Mut-G100E and Mut-G100N and a combined mutant Mut-A69N-G100N show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, and the contradiction that the traditional carbonyl reductase is easy to inactivate at high temperature and the catalytic efficiency is difficult to achieve at the same time is solved. The invention provides an efficient and stable enzyme catalysis tool for green biological preparation of chiral drug intermediates.

The invention belongs to the field of bioengineering, and particularly discloses a tryptophan synthetase mutant with improved enzymatic activity and application of the tryptophan synthetase mutant in production of L-cysteine. Compared with wild tryptophan synthetase from escherichia coli, the amino acid sequence of the tryptophan synthetase mutant has the advantages that a beta catalytic subunit has T69A, S143A, R219E and F280H site combined mutation. Researches show that the enzyme activity of the mutant is increased by 2.4 times compared with that of a wild type through enzyme activity determination and analysis of inducible expression and purification. The beneficial tryptophan synthetase mutant provided by the invention can efficiently biocatalyze L-serine and sodium hydrosulfide to synthesize L-cysteine, and has a better industrial application prospect.

The invention relates to the technical field of gene engineering and enzyme engineering, in particular to an esterase mutant for degrading ethyl carbamate and application of the esterase mutant, the esterase mutant has an amino acid sequence as shown in SEQ ID NO.1 which is subjected to site mutation, the site mutation is any one or more site combined mutation of V129S, V161L or I229M, and the amino acid sequence of the esterase mutant is shown in SEQ ID NO.1. The V129S site mutation is that valine at the 129 site is mutated into serine, the V161L site mutation is that valine at the 161 site is mutated into leucine, and the I229M site mutation is that isoleucine at the 229 site is mutated into methionine. Mutation is carried out through a site-directed mutagenesis method, so that the amino acid sequence of the esterase mutant V129S / I229M is changed, the autoplasmic structure and function of eggs are changed, the esterase mutant V129S / I229M with the ethyl carbamate hydrolysis rate increased to 6.55 times in an acid environment is finally obtained, and the esterase mutant V129S / I229M has high industrial application value.

The invention discloses a tryptophan synthase mutant as well as a coding gene, a vector, recombinant bacteria and application thereof. Comprising the following steps: carrying out error-prone PCR (Polymerase Chain Reaction) on a coding gene trpBA of TrpS from EscherichiaoliK12MG1655, screening mutants by combining high-throughput screening, and finding that the affinity of the TrpS to a substrate indole can be effectively improved by mutating 114-site Gln of a beta subunit of the TrpS into Met and mutating 84-site Gly into Ser, so that the synthesis of L-tryptophan is promoted. The efficiency of the TrpS for converting indole and L-serine into L-tryptophan is higher due to the improvement of the affinity of indole. A new idea is provided for efficient production of L-tryptophan in the fermentation industry.

The invention belongs to the field of enzymatic preparation of structural phospholipids, and particularly relates to a method for preparing phosphatidylserine through interfacial enzyme catalysis. A series of high-activity immobilized phospholipase are prepared by innovatively adopting bifunctional group modified hollow mesoporous silica microspheres as a carrier and adsorbing immobilized phospholipase D. The catalyst has the functions of a catalyst and an emulsifier, and a Pickering emulsion interfacial enzyme catalysis system can be efficiently constructed. In the system, the phosphatidylcholine and the serine are efficiently converted into the phosphatidylserine through a phosphatidyl transfer reaction, the conversion rate of the phosphatidylserine within 20 minutes can reach 85%-95%, and the catalytic efficiency reaches up to 372 mmol / (g.h). In addition, after the catalyst is recycled for 10 times, the conversion rate is still kept at 70.9%, and the catalyst shows excellent stability and reusability. The method has the remarkable advantages of being mild in reaction condition, high in catalytic efficiency, capable of being repeatedly used and the like, and a new technical approach is provided for industrial production of phosphatidylserine.

The invention discloses a cyclic nonapeptide with repairing and anti-oxidation effects and application of the cyclic nonapeptide, the amino acid sequence of the cyclic nonapeptide is cyclic (arginine-glycine-aspartic acid-serine-arginine-lysine-valine-lysine-serine), the prepared cyclic nonapeptide has the repairing and anti-oxidation effects, and the cyclic nonapeptide has the repairing and anti-oxidation effects. The composition can be applied to preparation of cosmetics with repairing and / or anti-oxidation effects.

The invention provides a method for preparing high-purity phosphatidylserine by a batch enzyme catalysis method based on dynamic choline removal, and belongs to the technical field of enzymatic reaction. According to the method disclosed by the invention, in a reaction system for preparing phosphatidylserine, a byproduct choline is selectively adsorbed by adopting resin. Choline in a reaction system is removed in real time through the integrated adsorption separation module, the enzyme inhibition problem is solved, and meanwhile, the PC conversion rate is larger than or equal to 98% and the PS purity is larger than or equal to 96% in combination with the immobilized enzyme circulation technology; the enzyme can be reused for more than or equal to 20 times (activity retention is more than or equal to 90%); and the choline residual concentration is less than or equal to 0.5 mM (an inhibition threshold value or less).

The present invention discloses a complete medium for culturing DF-1 cells, including DMEM basal medium 13.7g / L, insulin, non-essential amino acids, transferrin, glutathione, ascorbyl phosphate, sodium selenite, ethanolamine, hydrocortisone, and newborn calf serum. Wherein non-essential amino acids include glycine, alanine, proline, serine, and asparagine. A complete medium for culturing DF-1 cells provided by the present invention can well promote the proliferation of DF-1 cells, can achieve the same proliferation effect as high-concentration fetal bovine serum, and is suitable for the adherent culture of DF-1 cells; using low-concentration newborn calf serum, it is possible to greatly avoid the batch differences, unstable culture results, cytotoxicity, and high risk of carrying pathogens brought by the culture medium with high-concentration serum, narrow application range, expensive fetal bovine serum, and high culture cost; the components are simple, the culture medium preparation process is short in time consumption, the culture efficiency is high, the repeatability is good, and it is suitable for batch production.

The invention discloses keratinase Phyto-Keratinase and application of the keratinase Phyto-Keratinase. The keratinase Phyto-Keratinase comprises the following components: (1) protease which is coded by a nucleotide sequence as shown in SEQ ID NO.1; and / or (2) protease which is derived from bacillus subtilis, is coded by a nucleic acid sequence with more than 98% of identity with the SEQ ID NO.1 nucleotide sequence and has the characteristic of hydrolyzing keratin. According to the plant keratinase Phyto-Keratinase disclosed by the invention, the Phyto-Keratinase (plant keratinase) produced by utilizing microbial fermentation is a serine proteolytic enzyme, is also a biocompatible cutinase, and is obtained by fermenting saccharomyces cerevisiae. Phyto-Keratinase provides a nitrogen source for the growth of plants (beans), and contains various amino acids (functional peptides) and special proteolytic enzymes derived from the plants at the same time. The Phyto-keratinase can provide the effects of resisting inflammation, removing cutin and providing nutrition for skin regeneration at the same time, can relieve various inflammations by inhibiting PAR-2 receptors, and has potential value in the fields of cosmetics, beauty medicine and environment.

The present disclosure provides for improved compositions of ionizable lipid nanoparticles for the delivery of therapeutic nucleic acids to cells. Anionic phospholipids, including phosphatidylserine and phosphatidylglycerol are included in the lipid nanoparticles to increase the transfection efficiency in human dendritic cells. The further incorporation of mono-unsaturated alkyl chain analogs in dimethylaminopropyl-dioxolane or heterocyclic ketal ionizable lipids in the formulation demonstrated high levels of transfection in human dendritic cells, compared to other ionizable lipids in the same family, and demonstrated good stability to oxidative damage. Finally, the use of an ammonium salt of phosphatidylserine allows for the efficient production of PS-targeted LNPs.

The invention relates to the technical field of carotenoid cleavage dioxygenase, and discloses a carotenoid cleavage dioxygenase mutant and application thereof. In order to improve the efficiency of converting carotenoid in tobacco into aroma molecule beta-ionone, specific mutation of characteristic sites is carried out on carotenoid cleavage dioxygenase (PhCCD1) from petunia, that is, serine (S) at the 428 site of the carotenoid cleavage dioxygenase is mutated into cysteine (C) or tyrosine (Y) to obtain a mutant S428C or S428Y, and the mutant S428C or S428Y is converted into beta-ionone. The yield of the beta-ionone converted from the carotenoid is greatly improved. Experiments prove that the yields of beta-ionone of S428C and S428Y respectively reach 54.2 mg / L and 50.6 mg / L, which are respectively increased by 69.7% and 58.5% compared with those of a wild strain WT.

The invention belongs to the technical field of biology, and particularly relates to application of serine in relieving heat stress of pleurotus ostreatus and a method. Under the heat stress condition, exogenous serine supply promotes pleurotus ostreatus hypha to recover growth, and the activity of antioxidant enzyme, the yield of sporocarp and the yield of nutrient substances are improved; when the activity of the PHGDH enzyme is inhibited, the serine synthesis is reduced; the hypha growth can be promoted by overexpressing the phgdh, and the enzymatic activity of the PHGDH can be improved; when acetyltransferases HAT, NAT1, NAT2 and NAT3 act on a K394 site of the PHGDH, the enzyme activity of the PHGDH can be improved, endogenous serine metabolism is activated to respond to heat stress, it is indicated that PHGDH-mediated serine metabolism plays an important role in corresponding heat stress of the pleurotus ostreatus, and the invention discloses a mechanism for improving heat resistance of the pleurotus ostreatus through the PHGDH-mediated serine metabolism. And a foundation can be laid for breeding high-temperature-resistant pleurotus ostreatus dominant strains.

The invention relates to a TaCBL4 mediated TaSOS1 phosphorylation regulation and control site in wheat and an application of the TaCBL4 mediated TaSOS1 phosphorylation regulation and control site. The TaSOS1 phosphorylation regulation and control site is Ser978-Ser1126 / Ser1128 (S978-DSPS); the phosphorylation regulation and control site of the TaSOS1 is S978-DSPS, and serine at the site 978 of the TaSOS1-DAA (S1126AS1128A) is mutated into alanine. The TaSOS1 in the wheat is from a chromosome LOC778390, NC057800.1 (13146069..13157356) of the 3A of the common wheat, and the TaSOS1 in the wheat is from a chromosome NC057800.1 (13146069..13157356). The invention also relates to an application of the TaCBL4 mediated TaSOS1 phosphorylation regulation site Ser978-Ser126 / Ser128 (S978-DSPS) in the wheat as a molecular marker for detecting the salt tolerance of the wheat, and also relates to an application of the TaCBL4 mediated TaSOS1 phosphorylation regulation site. The site is applied to the aspects of wheat salt tolerance improvement and assisted breeding.

The invention relates to the technical field of related drugs for nerve injury caused by heavy metal pollution, in particular to application of a compound for inhibiting phosphorylation of ARMC10 in preparation of drugs for antagonizing tin-induced nervous system injury. Exposure of trimethyltin chloride induces nerve cell mitochondrial dysfunction, and the key mechanism is ARMC10 serine 43 site abnormal phosphorylation. Phosphorylated protein causes excessive mitochondrial fission, membrane potential collapse and energy metabolism disorder, resulting in neuron damage. Based on the target spot, a compound for antagonizing tin-induced nervous system injury is obtained through screening, protein phosphorylation can be specifically inhibited, mitochondrial dynamic unbalance and dysfunction induced by trimethyltin chloride are effectively reversed, and neurotoxicity is relieved. According to the technical scheme, the technical problem that in the prior art, no medicine for effectively antagonizing tin-induced nervous system injury exists can be solved, and the compound has the application potential for treating the nervous system injury and cognitive impairment caused by tin exposure.

The invention relates to the technical field of functional food and biological medicine, in particular to a modified pseudo-ginseng exosome and an intestinal conditioning gel composition and application thereof. According to the gel beverage, an exosome derived from panax notoginseng callus cultured in a laboratory is used as a core active component, is modified through phosphatidylserine-aminated pectin-genipin and is embedded into a hydrogel matrix composed of carboxymethyl chitosan and sodium alginate, so that the exosome is protected from being degraded in the stomach, and the activity of the exosome in the stomach is improved. The exosome can be effectively released under the intestinal pH and flora environment, so that the targeted delivery of the intestinal tract is realized, and the preparation method is suitable for improving the intestinal inflammation and maintaining the intestinal health. The invention can effectively solve the technical problems of uncontrollable raw material quality and safety, low oral delivery stability and active ingredient availability and poor medication compliance of the existing plant exosome.

The invention discloses a yak bone collagen peptide for improving osteoporosis and preparation and application thereof, and relates to the field of biological medicine, the yak bone collagen peptide comprises collagen peptide with the molecular weight of 500-2000 Daltons, contains a glycine-proline-hydroxyproline tripeptide core structure, can promote osteoblast differentiation and inhibit osteoclast activity, and can be used for treating osteoporosis. The amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine, and the amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine; and the amino acid is glycine, proline, hydroxyproline, serine, leucine and alanine. The yak bone collagen peptide has a unique glycine-proline-hydroxyproline tripeptide structure, the molecular weight is controlled within the range of 500-2000 Daltons, the structure can promote osteoblast differentiation and inhibit osteoclast activity at the same time, and the problem that a traditional osteoporosis treatment medicine is single in function is solved.

Among other things, provided herein are systems that replace the natural random integration activity of a retrovirus with site-specific integration machinery. This approach allows for a more precise targeting of a gene of interest into a human genome, e.g., for therapeutic purposes. The system may include integration-deficient retrovirus (e.g., lentivirus) (IDLV), in which the natural integration activity has been reduced (e.g., by mutation to the viral integrase polypeptide). Instead, the system may comprise a site-specific recombinase (e.g., a serine recombinase, e.g., a serine integrase) capable of directing insertion of a template DNA, or portion thereof, into a desired site in the human genome.

The invention belongs to the technical field of triple negative breast cancer, and particularly relates to application of a polypeptide capable of specifically blocking phosphorylation of metabolic enzyme PSAT1S337 and functional remodeling of PSAT1 in preparation of a triple negative breast cancer treatment product. The phosphorylated polypeptide targeting PSAT1S337 is designed, and it is found that the polypeptide obviously inhibits growth of triple negative breast cancer tumors and can improve the curative effect of anti-PD-1 immunotherapy at the animal level. Meanwhile, the invention further provides application of the reagent for detecting the phosphorylation level of the PSAT1S337 and / or the hydroxylation level of the GPX4P159 in preparation of products for diagnosing and prognosing the triple negative breast cancer. The invention discloses a molecular mechanism of functional remodeling of the serine metabolic enzyme PSAT1 in occurrence and development of cell ferroptosis and triple negative breast cancer, and provides a new thought and an effective scheme for research and development of anti-tumor drugs for targeted serine metabolism reprogramming and early diagnosis of tumors.

The invention discloses an Escherichia coli endogenous alcohol dehydrogenase EcYjgB mutant and application thereof. The mutant is obtained by performing any one of the following mutations (a) to (c) on Escherichia coli endogenous alcohol dehydrogenase EcYjgB as shown in SEQ ID NO.1: (a) mutating serine at the 200th site into arginine; (b) the serine at the 199th site is mutated into aspartic acid, and the serine at the 200th site is mutated into arginine; and (c) the serine at the 199th site is mutated into aspartic acid, the serine at the 200th site is mutated into arginine, and the asparagine at the 240th site is mutated into tryptophan. The mutant is used for efficiently catalyzing reduction of HMF or furfural to respectively synthesize BHMF and furfuryl alcohol, so that the purposes of improving the production efficiency, reducing the production cost and improving the environmental effect are achieved.

The invention discloses an amino acid composition for treating alopecia and application of the amino acid composition in preparation of a medicine for treating alopecia, and belongs to the field of medicine configuration products, the amino acid composition is composed of a targeting core intervention component and an auxiliary strengthening synergistic component, the targeting core intervention component is prepared from 30-50 parts of arginine, 50-155 parts of lysine and 50-120 parts of glutamic acid, and the auxiliary strengthening synergistic component is prepared from an auxiliary strengthening synergistic component and an auxiliary strengthening synergistic component. 10 to 40 parts of cysteine and 20 to 60 parts of leucine; the auxiliary strengthening synergistic component is prepared from 15 to 45 parts of tyrosine, 15 to 40 parts of glycine, 10 to 40 parts of glutamine, 20 to 35 parts of serine, 5 to 25 parts of alanine, 2 to 20 parts of aspartic acid and 15 to 35 parts of phenylalanine; the composition can be used as an active ingredient to be prepared into different dosage forms such as a pigmentum, a spray, an ointment and a liniment, is applied to prevention of alopecia and promotion of hair growth, and has a remarkable treatment effect.

The invention discloses a tryptophan synthetase trp B modified gene and a preparation method of 6-fluoro-L-tryptophan, belongs to the technical field of gene modification and amino acid synthesis, and provides a tryptophan synthetase trp B gene subjected to mutation modification, and the nucleotide sequence of the tryptophan synthetase trp B gene is shown as SEQ ID NO.1. After gene modification, substrate molecules can enter the channel more easily. After gene modification, a channel of an active center of tryptophan synthetase is more beneficial to entering of substrates 6-fluoroindole and L-serine, and the yield of 6-fluoro-L-tryptophan is increased. According to the method, a specific strain containing tryptophan synthetase is adopted, tryptophan synthetase can be efficiently expressed by culturing in an optimized culture medium, so that the 6-fluoro-L-tryptophan synthesized by an enzymic method has relatively high catalytic rate and conversion rate, the molar conversion rate of L-serine reaches 86.5% or above, the reaction conditions of the enzymic method synthesis are mild, the enzyme stereoselectivity is strong, the catalytic efficiency is high, and the method is suitable for industrial production. The method is suitable for industrial production.

According to the scheme, the invention provides the recombinant macrolide enzyme as well as the preparation method and the application thereof, the amino acid sequence of the recombinant macrolide enzyme is as shown in SEQ ID NO.1, and the recombinant macrolide enzyme is derived from an EreC esterase family of enterobacter hormaechei and is obtained through site-specific mutagenesis; the mutation sites are as follows: glutamic acid at the 44th site is mutated into asparagine, tyrosine at the 55th site is mutated into proline, proline at the 76th site is mutated into arginine, phenylalanine at the 153rd site is mutated into alanine, and serine at the 219th site is mutated into glutamic acid. The method is expected to remove macrolide antibiotic pollution, and has good economic benefits and practical values.

The present invention belongs to the field of biotechnology and pharmaceutical engineering technology, and discloses a functionalized drug-loaded exosome based on milk exosomes, a preparation method thereof, and an application thereof. The functionalized drug-loaded exosomes include a carrier and a water-insoluble drug, and the water-insoluble drug is loaded inside the carrier; wherein the surface of the carrier is loaded with milk exosomes with functionalized molecules, and the functionalized molecule is any one of phosphatidylserine, a molecule capable of macrophage targeting, and a molecule or polymer that enhances the targeting and stability of milk exosomes; the water-insoluble drug is any one of an antibacterial drug, an antitumor drug, and a gene drug. The functionalized drug-loaded exosomes in the present invention can improve the gastrointestinal stability of oral administration and enhance the efficacy against bacterial pathogens; expand the application scope of milk exosomes in the fields of anti-intestinal bacterial infection and food preservation, and the exosome content in milk is very rich, which is convenient for large-scale preparation and has important application value.

Among the various aspects of the present disclosure are compounds that are useful for inhibiting one or more proteases including various serine proteases such as Hepatocyte Growth Factor Activator (HGFA), and the type II transmembrane serine proteases (TTSPs) including matriptase, hepsin, and TMPRSS2. The present invention also relates to various methods of using the inhibitor compounds to treat and / or prevent infections and their symptoms / complications, including those caused by coronaviruses and influenza viruses, conditions associated with inflammation, various other malignancies, pre-malignant conditions, and / or cancer.

The present invention relates to a composition comprising, preferably consisting of, (i) a single empty liposome, wherein said single empty liposome is selected from (a) an empty liposome comprising cholesterol, wherein the amount of cholesterol is at least 30% (weight per weight), wherein preferably said empty liposome comprising, further preferably consisting of, cholesterol and sphingomyelin; or (b) an empty liposome consisting of sphingomyelin; or (ii) a mixture of empty liposomes; wherein said mixture of empty liposomes comprises, preferably consists of, at least one empty liposome selected from (a) an empty liposome comprising cholesterol, wherein the amount of cholesterol is at least 30% (weight per weight), wherein preferably said empty liposome comprising, further preferably consisting of, cholesterol and sphingomyelin; (b) an empty liposome consisting of sphingomyelin; and (c) an empty liposome comprising, preferably consisting of, phosphatidylcholine and sphingomyelin; and at least one empty liposome independently of each other selected from an empty liposome comprising, preferably consisting of, lipids or phospholipids selected from cholesterol, sphingomyelins, ceramides, phosphatidylcholines, phosphatidylethanolamines, phosphatidylserines, diacylglycerols, and phosphatidic acids containing one or two or more saturated or unsaturated fatty acids longer than 4 carbon atoms and up to 28 carbon atoms; for use in a method for preventing or reducing biofilm formation or for eradicating or reducing existing biofilm.

The invention discloses an engineered glycosyl transferase and application thereof in efficient preparation of triterpenoid saponin. The engineered glycosyl transferase is obtained by mutating serine at the 15th site of UGT74AC1 enzyme into alanine, mutating histidine at the 47th site into aspartic acid, mutating leucine at the 48th site into valine, mutating alanine at the 180th site into serine, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid The mutant is obtained by mutating serine at the 332 site into proline, phenylalanine at the 367 site into tryptophan and lysine at the 420 site into arginine. According to the invention, the glycosyl transferase with high catalytic activity is obtained by modifying an enzyme engineering technology, and good application of the glycosyl transferase in synthesis of triterpenoid saponin is realized. The glycosyl transferase disclosed by the invention can also be coupled with sucrose synthase, or coupled with N-acetylhexosamine kinase and N-acetylglucosamine-1-uridine phosphate transferase, and acetylglucosamine is used as a glycosyl donor, so that cascade production of triterpenoid saponin with lower cost and higher efficiency is realized.

Engineered, modified, or mutated Bacillus strains that produce keratinases or serine proteases (KerS) that biologically degrade keratin-containing materials, such as feathers; compositions containing these Bacillus strains or the keratinases they produce, and methods for biologically degrading keratin-containing materials using these strains or keratinases.

The invention discloses a penicillin G acylase mutant with high synthetic activity and low hydrolytic activity and application of the penicillin G acylase mutant, and belongs to the field of bioengineering. The penicillin G acylase gene derived from Escherichia coli is subjected to site-specific mutagenesis, so that the amino acid sequence coded by the penicillin G acylase gene mutates from phenylalanine F to alanine A at the 24th site of an alpha chain, the 146th site of the alpha chain mutates from phenylalanine F to valine V, and the 386th site of a beta chain mutates from serine S to alanine A to obtain the mutant. According to the penicillin G acylase mutant alphaF24A / betaS386A disclosed by the invention, compared with the conversion rate of cefamandole synthesized by catalyzing the reaction of methyl mandelate and 3-(1-methyl-1H-tetrazole-5-yl) thiomethyl-7-aminocephalosporanic acid (7-TMCA) within 4 hours before mutation, the conversion rate of cefamandole synthesized by catalyzing the reaction of methyl mandelate and 3-(1-methyl-1H-tetrazole-5-yl) thiomethyl-7-aminocephalosporanic acid (7-TMCA) is improved by 13.70%, and the yield of a side reaction product mandelic acid is reduced by 82%. The penicillin G acylase mutant disclosed by the invention can be used for catalyzing methyl mandelate and 7-TMCA to synthesize cefamandole while greatly reducing the occurrence of side reactions, and can be applied to preparation of cephalosporin antibiotics.

The present invention provides a food composition comprising a plurality of amino acids or salts thereof wherein the amino acids or salts thereof comprise from about 0.0016 to 0.6 wt% of glycine or salts thereof and from about 0.00109 to 1.2 wt% of serine or salts thereof. Also provided is a method of treating cancer in a subject comprising partially or completely replacing or replacing the normal diet of the subject with the food composition, and optionally administering to the subject an effective therapeutic amount of an anti-PD-1 antibody or an anti-PD-L1 antibody.