294 results about "Glycosidic bond" patented technology

The invention discloses a method for efficient conversion and utilization of mogroside. According to the method, mogroside V is converted through fermentation of candida parapsilosis L7, and siamenoside I is directionally synthesized. According to the invention, Candida parapsiloides L7 is utilized for fermentation conversion, and beta-1, 6-glucosidic bonds in glucose branched chains connected with C3-site hydroxyl of a mogroside V structure parent nucleus can be directionally hydrolyzed with high regioselectivity (the beta-1, 6-glucosidic bonds on glucose branched chains connected with C24-site hydroxyl are hardly hydrolyzed), so that one molecule of glucose is removed, and siamenoside I is obtained. The siamenoside I provided by the invention can be efficiently prepared, and the maximum molar yield of the siamenoside I can reach 87.40%. The siamenoside I has more obvious selective hydrolysis characteristic, higher space time yield of the siamenoside I, no cytotoxicity of the siamenoside I and better anti-inflammatory and antioxidant activity, provides a new drug choice for diseases such as inflammation and the like, and provides technical support for development of high-valued products of mogroside.

The invention relates to the technical field of plant polysaccharide extraction, in particular to a process for synergistically extracting rape pollen polysaccharide by a compound enzyme, which comprises the following steps: crushing rape pollen to 200-300 meshes by pulse airflow, performing microwave-ultrasonic degreasing by using a 85% ethanol solution, mixing with an acetic acid-sodium acetate buffer solution with the pH value of 4.8, and performing ultrasonic extraction to obtain a crude extract; the method comprises the following steps: adding a compound enzyme system which is immobilized by Fe3O4 (at) SiO2 nanoparticles by cellulase, pectinase, protease and beta-glucosidase according to a mass ratio of 2: 1: 1: 0.5, carrying out enzymolysis for 4 hours in a 50 DEG C constant-temperature water bath and a 15V / cm pulsed electric field, carrying out enzyme deactivation on enzymatic hydrolysate, carrying out gradient ethanol precipitation, carrying out ultrafiltration deproteinization, and carrying out vacuum pulsation freeze drying to obtain the polysaccharide. According to the method disclosed by the invention, the cell wall breakage rate and the enzymolysis efficiency are improved through pulsed airflow crushing, magnetic nano immobilized enzyme and pulsed electric field assistance, the polysaccharide yield reaches 7.32%, the purity is 91%, the beta-glucosidic bond proportion and the antioxidant activity are remarkably improved, the enzyme can be recycled and reused, the drying time is shortened, and efficient and low-consumption extraction is realized.

The invention relates to polystyrene cation exchange resin as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving a dispersing agent in a solvent to obtain a dispersed phase for suspension polymerization reaction, uniformly mixing a reaction monomer, a cross-linking agent, a pore-foaming agent and an initiator, and carrying out suspension polymerization reaction under segmented stirring and segmented temperature change to prepare copolymer microspheres; and putting the dried microspheres into a reaction kettle, swelling, carrying out sulfonation reaction through a variable temperature program on the basis to obtain sulfonated microspheres, and carrying out alkali exchange reaction on the sulfonated microspheres to obtain the final product cation exchange resin. Compared with the prior art, the cation exchange resin preparation method provided by the invention has the characteristics of simple and feasible process, easiness in large-scale production, low cost, high specific surface area, high adsorption capacity and high separation efficiency, and is especially suitable for separating and purifying substances containing amino groups or aminoglycosidic bonds.

The invention relates to a preparation method of high-substitution-degree cationic micro-nano cellulose and application of the high-substitution-degree cationic micro-nano cellulose to improvement of water filtering performance of paper. In the enzymolysis pretreatment process, beta-1, 4 glucosidic bonds among glucose molecules are cut off, and more reaction binding sites are created for cationization after cellulose in an amorphous region and a part of crystalline region is hydrolyzed, so that the use amount of chemical reagents can be effectively reduced, and the environmental pollution is reduced. The prepared high-substitution-degree cationic micro-nano cellulose (CMFC) has abundant positive charges, weakens the hydrogen-bond interaction of cellulose molecules, improves the content of nano-fibrillation, and effectively reduces the mechanical preparation energy consumption of the CMFC. CMFC pulp is added into paper pulp fibers, so that pores of the paper fibers are blocked, more filler is intercepted, and the filler is difficult to be completely brought into white water by water flow in the water filtering process, so that the retention rate is increased, and the water filtering performance is effectively improved.

The present invention provides a novel pressure-sensitive adhesive composition including a glucan derivative. The pressure-sensitive adhesive composition of the present invention includes a glucan derivative G having a glucoside bond A, and a glucoside bond B having a different bonding form from the glucoside bond A. The glucoside bond A is, for example, a 1,6-glucoside bond. A pressure-sensitive adhesive sheet 1 of the present invention is formed from the pressure-sensitive adhesive composition. A laminate 10 of the present invention includes the pressure-sensitive adhesive sheet 1 and a substrate sheet 2.

The invention discloses a method for improving moso bamboo cellulase hydrolysis conversion efficiency through amino acid-based deep eutectic solvent pretreatment, and belongs to the technical field of biomass recycling. The method comprises the following steps: mixing an L-cysteine solid and a formic acid solution, performing water bath heating to prepare an acidic eutectic solvent, performing microwave-assisted eutectic solvent pretreatment on moso bamboos, and performing filtration separation and enzymolysis; wherein the molar ratio of the L-cysteine to the formic acid is 1: (4-5). A deep eutectic solvent formed by formic acid and cysteine has a strong hydrogen bond network and an acid environment, beta-O-4 ether bonds in lignin are promoted to be broken, sulfydryl of cysteine participates in nucleophilic attack, a lignin-carbohydrate complex is further destroyed, formic acid can hydrolyze acetyl and glucosidic bonds in hemicellulose, and the lignin-carbohydrate complex is further destroyed. And degrading into an oligomer or monosaccharide. The phyllostachys pubescens components are efficiently separated, the cellulose enzymolysis saccharification capacity is improved, and effective utilization of all the phyllostachys pubescens components is facilitated.

The invention discloses hyaluronic acid endo-lyase and application thereof in preparation of hyaluronic acid with specific molecular weight. The hyaluronate lyase can cut a beta1-4 glucosidic bond to generate unsaturated oligosaccharide, has the characteristics of high enzyme activity and catalytic efficiency and good stability, and the enzymolysis reaction can be carried out in water without adding metal ions and a buffer solution, so that the hyaluronate lyase has the advantages of simplicity in product recovery and no need of removing salt. The hyaluronate lyase not only can be used for degrading hyaluronic acid, but also can be used for degrading chondroitin sulfate, not only can be used for preparing polysaccharide with specific molecular weight, but also can be used for completely degrading the polysaccharide into unsaturated disaccharide, and has a wide application prospect in the fields of cosmetics, food, health care products, medicines and the like.

The invention belongs to the technical field of chitosan oligosaccharide preparation, and particularly relates to a method for preparing chitosan oligosaccharide based on compound enzyme. According to the method for preparing the chitosan oligosaccharide based on the compound enzyme, a multi-enzyme synergistic system is matched with the design of a specific protective agent, chitosanase and chitinase can cooperatively cut beta-1, 4 glycosidic bonds of chitosan and control molecular weight distribution of products, meanwhile, chitinase can directionally cut the beta-1, 4 bonds at the tail end of chitosan, and the molecular weight distribution of the products is controlled. The papain is used for removing protein impurities in the chitosan to realize accurate control of the polymerization degree. Besides, a specific protective agent matched with the multi-enzyme synergistic system is specifically designed, the specific protective agent and the multi-enzyme composition act together, the molecular weight distribution width can be remarkably reduced, the yield and the DP 4-8 proportion can be increased, meanwhile, physical field ultrasonic assistance is added in the enzymolysis treatment process, and the enzymolysis treatment efficiency is improved. The combination of the substrate and the enzyme is further promoted, and the reaction time is shortened.

The invention discloses purified barley seedling polysaccharide as well as a preparation method and application thereof. The polysaccharide is prepared from six monosaccharides, namely rhamnose, galacturonic acid, glucose, galactose, xylose and arabinose in a molar ratio of 2.88: 3.39: 1.51: 1: 0.76: 3.2. The relative molecular weight is 254.09 kDa. A fermentation method is combined with an innovative purification process, so that the barley seedling polysaccharide monomer with high purity and uniform structure is obtained for the first time. Through a multi-dimensional characterization technology, fine structure characteristics such as monosaccharide composition, glucosidic bond connection mode and branching degree are systematically analyzed, and a reliable material basis is provided for establishing structure-function accurate association. The purified barley seedling polysaccharide has a remarkable effect of promoting intestinal peristalsis, not only lays a scientific foundation for deep processing of barley seedlings and research and development of related functional products, but also provides a new theoretical support for relieving intestinal peristalsis disorder, and has a wide application prospect.

The invention relates to the technical field of microbial engineering, and particularly discloses a compound microbial agent for treating cyanobacterial bloom, bacillus velezensis provided by the invention destroys algae cells and inhibits the activity of related biological enzymes by secreting heterocyclic algal killing active substances, and simultaneously causes the leakage of cellular contents (such as algal toxins, polysaccharides and lipids); an extracellular enzyme system (such as alkaline phosphatase and beta-glucosidase) of the sphingomonas decomposes free algal toxins into low-toxicity linear peptide fragments and hydrolyzes beta-1, 4-glucosidic bonds in EPS at the same time, so that algae-derived organic fragments are converted into small-molecular soluble substances, and a substrate is provided for follow-up metabolism of rhodococcus; lipase and esterase secreted by rhodococcus can hydrolyze triglyceride and waxy components, fatty acid is converted into energy and a biosurfactant through a beta-oxidation pathway, and hydrophilicity of frond fragments is enhanced to promote overall degradation efficiency.

The invention discloses an alpha-1, 4 glucosidic bond hydrolytic ability enhanced oligomerized 1, 6-glucosidase mutant and application thereof, and belongs to the technical field of gene engineering and enzyme engineering. The oligomerized 1, 6-glucosidase mutant V219A / P227A disclosed by the invention also has the alpha-1, 4 glucosidic bond hydrolytic activity which is not possessed by a wild type enzyme on the basis of retaining the original alpha-1, 6 glucosidic bond hydrolytic activity, and the alpha-1, 4 glucosidic bond hydrolytic activity is improved by 267% compared with that of a single mutant V219A. The mutant V219A / P227A is applied to an enzymatic production process of glucose, maltodextrin is taken as a substrate, glucamylase and the mutant V219A / P227A are added for enzymatic conversion, and the final glucose yield reaches 98.0%; the mutant V219A / P227A is applied to regeneration of glucose from crystalline glucose mother liquor, and the final glucose yield reaches 95.9%, which is 9.35% and 5.15% higher than those of a wild type V219A and a single mutant V219A respectively. Therefore, the mutant is helpful for improving the substrate conversion rate and the product purity in the glucose production process, can be used for regenerating glucose from crystalline glucose mother liquor, and has higher industrial application value.

To provide a technique capable of effectively recycling each recovered material as a single material by selectively decomposing, separating and recovering a fiber having a β - glycoside bond from a mixed fiber comprising the fiber having the β - glycoside bond such as cotton and other fibers such as polyester by a simple treatment in a short time under a non-pressurized condition.SOLUTION: A treatment method comprising selectively decomposing a fiber having a β - glycosidic bond from a mixed fiber containing the fiber having a β - glycosidic bond and a fiber composed of another material by a treatment using a deep eutectic solvent (DES) formed by mixing a hydrogen bond donor with a hydrogen bond acceptor at a molar ratio of 0.50 or more and 6.00 or less, and recovering the fiber composed of another material in a fibrous form.SELECTED DRAWING: None

The invention relates to the technical field of skin care products, in particular to a glucan product as well as a preparation method and application thereof. According to the invention, the glucan product is obtained by performing enzymolysis on the material containing the glucan through the incision enzyme for specifically treating the 1, 4 glucosidic bonds, and the number ratio of the 1, 4 glucosidic bonds to the 1, 3 glucosidic bonds in the glucan product is 1.8 or less, so that the intramolecular and intermolecular agglomeration of the glucan is improved, the room-temperature stability of the glucan is improved, and the yield of the glucan is increased. And the obtained glucan product can be added in cosmetics in a large amount, has a stronger anti-inflammatory effect, and has an outstanding effect of promoting skin soothing after being added into the cosmetics.

The present disclosure relates to poly alpha-1,6-glucan ether compounds comprising poly alpha-1,6-glucan substituted with at least one positively charged organic group and having a degree of substitution of about 0.001 to about 3.0. The poly alpha-1,6-glucan comprises a backbone of glucose monomer units, wherein greater than or equal to 40% of the glucose monomer units are linked via alpha-1,6 glycosidic bonds, and optionally about 3% of the backbone glucose monomer units have branches via alpha-1,2 and / or alpha-1,3 glycosidic bonds. Compositions comprising poly alpha-1,6-glucan ether compounds can be used in various applications.

The invention discloses high-purity resistant dextrin and a preparation method thereof, and the preparation method comprises the following steps: (1) adding 4, 3-alpha-glucosyltransferase into a maltodextrin aqueous solution or a starch solution treated by starch debranching enzyme to react, and after the reaction is finished, deactivating the enzyme; (2) adding alpha-amylase into a reactant in the step (1) to react, and deactivating the enzyme after the reaction is finished; (3) adding alpha-glucosidase into the reactant in the step (2) for reaction, and deactivating the enzyme after the reaction is finished; (4) adding saccharifying enzyme into the reactant in the step (3) to react, and deactivating the enzyme after the reaction is finished; and (5) adding yeast powder into the reactant in the step (4) for fermentation, filtering by a filter membrane after fermentation, collecting membrane filtrate, and drying to obtain the high-purity resistant dextrin. The preparation process is simple and efficient, the product purity is high, the proportion of alpha-1, 3 glucosidic bonds in the prepared resistant dextrin is 40% or above, and the purity of the resistant dextrin is 80-90%.

This invention discloses a method for determining the content of suberin monomers in the suberized tissue of yam tubers. Suberin is a macromolecular polyester, with monomers mainly covalently linked by oxygen-ester bonds. Its aliphatic compounds are linked to the polysaccharide components in the cell wall by glycosidic bonds and located on the inner side of the cell wall. Therefore, to determine the suberin monomer content, it is necessary to first destroy the plant cell structure, and then hydrolyze the oxygen-ester bonds between the suberin monomers to release the suberin monomer components. This invention first uses ultrasonic pretreatment to destroy plant cells, and then uses lipase hydrolysis combined with ultrasonic assistance and acid hydrolysis (sulfuric acid / methanol) to fully and efficiently hydrolyze the suberin into monomers. The reagents used are relatively safe and non-toxic, and the operation is relatively simple, solving the technical problem of difficult determination of suberin monomer content in the study of suberin metabolism after yam tuber injury healing.

A surface treatment composition for increasing permeability in a hydrocarbon shale formation during stimulation containing a solvent and an effective amount of at least one of a quaternary monosaccharide having from about 1 to 3 moles of quaternary functional groups of and a quaternary saccharide having a number of the monosaccharide molecules ranging from about 2 to 20 bonded together by glycosidic linkage with from 1 to 3 moles of quaternary functional groups per molecule of the monosaccharide in the saccharide. A method of using the surface treatment for increasing permeability in a hydrocarbon shale formation during stimulation.

The invention discloses an exosome slow-release oral soluble film based on enzyme triggering and a preparation method thereof. The oral soluble film comprises a film forming substrate, a plasticizer, a disintegrating agent, mucous membrane adhesion type enzyme-sensitive nanogel and a stable protection component. Wherein the mucous membrane adhesion type enzyme-sensitive nanogel has a three-layer functional structure: an enzyme-sensitive cross-linking core is formed by maleimide starch through gradient cross-linking, and alpha-1, 4 glucosidic bonds on a starch chain can be hydrolyzed by saliva alpha-amylase; the phospholipid-exosome composite layer is located on the surface of the core, and efficient embedding of the exosome is achieved through a pre-fusion-cold locking process; the mucous membrane adhesion layer is made of thiolated mucous membrane adhesion materials and can form disulfide bonds with oral mucosa. Self-regulation slow release insensitive to saliva alpha-amylase concentration fluctuation is realized through a gradient cross-linked structure, the problems of exosome activity loss, uncontrollable release and weak adhesion are effectively solved, and the exosome is suitable for treatment of oral mucosa diseases.

A prebiotic oligosaccharide composition for use in reducing branched short chain fatty acids (BSCFAs). The composition comprises oligosaccharide compounds, for example galactooligosaccharide compounds, which includes: (a) at least 8 wt % Gal-(β1-3)-Gal-(β1-4)-Xa; (b) at least 3 wt % Gal-(β1-3)-Gal-(β1-3)-Xb; and (c) at least 5 wt % Gal-(β1-3)-Gal-(β1-2)-Xc, based on the total weight of oligosaccharide compounds present in the composition; wherein Xa, Xb and Xc are each independently selected from monosaccharides. These compositions contain relatively high amounts of the oligosaccharide compounds (a), (b) and (c) and a relatively high amount of β1-3 Gal-Gal linkages, compared to known oligosaccharide compositions. The present invention also relates to a composition comprising oligosaccharide compounds for administration to the athletes and / or sports persons who are undergoing and / or are about to undergo physical training, and in particular those athletes and / or sports person on a high protein diet. A method of preparing said composition and the use of said composition as a dietary supplement or a medicament are also disclosed.

The application discloses a method for controllably degrading glycosidic bonds of hyaluronic acid by programmed temperature rising. The method is used for high-molecular-weight hyaluronic acid aqueous solution, and a combination of an oxygen oxidant and an acidic additive is used to controllably cut and degrade glycosidic bonds in the macromolecule through a heating process of programmed temperature rising control system, so as to obtain oligomeric hyaluronic acid. The oligomeric hyaluronic acid prepared by the method has very good stability and no color change after long-time storage. The oligomeric hyaluronic acid prepared by the method can be applied to the fields of cosmetics, food, medicine and the like, and has very strong practical value.

The invention discloses a flavor modifier, atomized essence and an aerosol generating device, and relates to the technical field of essence. According to the technical scheme, the flavor modifier comprises an active agent, a compound containing a phenolic hydroxyl group and-O-beta-D-glucosidic bond or a compound containing an alcoholic hydroxyl group and-O-beta-D-glucosidic bond is selected as the active agent, and the flavor modifier can be weakly combined with a Piezo channel in a trigeminal nerve to directly modulate a trigeminal nerve mechanoreceptor, so that the flavor of the trigeminal nerve is improved. The activity of the Piezo channel is inhibited, so that the sensitivity of the Piezo channel to mechanical friction of aerosol particles is reduced, and the nasal cavity roughness is reduced. Meanwhile, the flavor modifier disclosed by the invention can also cooperate with olfactory signals transmitted by other components in the atomized essence to jointly improve the smoothness, the fineness and the overall moist feeling of the fragrance.

The invention discloses a hederacoside C deglycosylation derivative and a preparation method and application thereof.The hederacoside C deglycosylation derivative is prepared from hederacoside C through specific glycosidase hydrolysis, different products can be flexibly regulated and enriched on the basis of selectivity of different glycosidase to glucosidic bonds and glycosyl sites, the preparation method is simple, reaction conditions are mild, and the hederacoside C deglycosylation derivative is suitable for industrial production. The method is suitable for large-scale mass production. The hederacoside C deglycosyl derivative does not show obvious cytotoxicity to human immortalized keratinocytes, has the effect of promoting cell proliferation and the activity of promoting cell migration, and can obviously inhibit LPS (lipopolysaccharide)-induced cell apoptosis. Besides, the partial hederacoside C deglycosyl derivatives can reduce inflammatory factor level rise caused by wounds, remarkably promote wound healing and reduce formation of wound scars, and have good application prospects in preparation of drugs or skin care products for promoting wound repair.

The present application relates to starch production technical field, especially disclose a kind of green preparation method for modified starch for replacing hydroxypropyl distarch phosphate.The green preparation method, cassava starch is used as raw material, specifically includes the following steps: (1) cassava starch is mixed with water uniformly, and starch suspension is prepared;(2) adding alpha-amylase to starch suspension for glycosidic bond enzymolysis, then passivate enzyme activity;(3) the enzymatic hydrolysate is used to hexose oxidase and oligomeric glucan is subjected to lactonization reaction, then passivate enzyme activity;(4) the final enzymatic hydrolysate is centrifuged, washed with water, the precipitate is freeze-dried, and enzyme modified cassava starch is obtained.The paste viscosity, freeze-thaw stability, shear resistance, anti-aging and other chemical properties of the enzyme modified cassava starch prepared by the present application are close to or better than hydroxypropyl distarch phosphate, and the preparation process is simple, short cycle, green and safe, low in production cost, simple in equipment, suitable for industrial production, and safe and pollution-free during production.

The invention discloses a compound microorganism fermented attenuated aroma-enhanced potato residue feed and a preparation method thereof, and belongs to the field of feed processing. The feed comprises potato residues, crop straw particles, corn flour, bran, soybean meal, urea, ammonium sulfate and a compound microbial agent, wherein the compound microbial agent comprises bacillus velezensis and lactobacillus plantarum. The preparation method comprises raw material pretreatment; preparing a microbial agent; performing mixed fermentation; and post-processing. The bacillus velezensis secretes glycosidase, and glucosidic bonds of the glycoalkaloid are subjected to enzymolysis; lactobacillus plantarum is metabolized to generate lactic acid to create an acidic environment to promote chemical degradation of glycoalkaloid, and the double bacteria cooperate to inhibit growth of mould, so that efficient attenuation is realized. The bacillus velezensis metabolizes to generate glucose, ethanol and free amino acid, and the lactobacillus plantarum metabolizes to generate ester flavor substances, so that the feed is endowed with strong fermentation aroma. Meanwhile, the pungent smell of volatile aldehyde substances is eliminated through double-bacterium synergism.

The invention provides emblic leafflower fruit polysaccharide with a weight losing effect and an efficient preparation method and application thereof, and belongs to the field of plant polysaccharide. The preparation method comprises the following steps: performing powdering, water extraction and concentration on a phyllanthus emblica raw material, adding an alcohol solvent for precipitation, and drying to obtain phyllanthus emblica crude polysaccharide; after the phyllanthus emblica crude polysaccharide is dissolved, impurities are removed through membrane filtration, protein substances are adsorbed through a reversed-phase chromatographic column, flow-through liquid and water leacheate are collected and combined, small-molecular-weight substances are removed through a membrane bag, intercepted liquid is collected and dried, and the phyllanthus emblica polysaccharide is obtained. The phyllanthus emblica polysaccharide has alpha-type and beta-type glycosidic bonds, and has linear polysaccharide chains and aggregates formed by a plurality of chains. The emblic leafflower fruit polysaccharide is used for preparing products for reducing fat and blood sugar, and can also be used for preparing medicines for preventing and treating abnormal glucose metabolism, abnormal lipid metabolism, related diseases, obesity and liver injury caused by obesity. The phyllanthus emblica polysaccharide extraction and purification preparation method is simple and efficient, and is convenient for industrial implementation.

To provide production methods to reduce production cost of sesaminol or sesaminol glycosides.SOLUTION: Disclosed is a method for producing sesaminol or sesaminol glycosides comprising a step of: reacting a protein with a substrate sesaminol glycoside having at least one glycoside linkage for catalyzing hydrolysis of the at least one glycoside linkage, where the protein is selected from the group consisting of: (1) a protein composed of a specific amino acid sequence; (2) a protein composed of an amino acid sequence having deletion, substitution, insertion and / or addition of one or more amino acids in the specific amino acid sequence and having the activity to catalyze hydrolysis of at least one glycoside linkage; (3) a protein composed of an amino acid sequence with 60% or more sequence identity to the specific amino acid sequence and having the activity to catalyze hydrolysis of at least one glycoside linkage.SELECTED DRAWING: Figure 8

A β-glucan composition and use thereof. Specifically provided are uses of the β-glucan composition in preparing a composition for improving or treating immune-related diseases, said β-glucan being a β-glucan containing β-1,3 and β-1,6 glucosidic bonds in the molecules thereof, and having a molecular weight of 1-50 kDa. The β-glucan features a novel structure, a controllable mass, abundant sources, simple preparation processing, high product purity, strong biological activity, and is easy to produce industrially, among other strengths. The resulting water soluble β-glucan composition features better antitumor activity, has the potential to be developed into a safe and effective novel drug for improving or treating immune-related diseases and fighting tumors.

The invention particularly relates to 4 '-thiosugar and a preparation method thereof. The preparation method comprises the following steps: taking D-ribose as a raw material, firstly carrying out methylation protection on C1-site hydroxyl, and then carrying out benzylation protection on other hydroxyl; the preparation method comprises the following steps: firstly, carrying out hydrolysis on a glucosidic bond at a C1 site, carrying out reduction through hydroboron to obtain open-loop ribitol (formula V), carrying out sulfonic acid esterification and bromination substitution on hydroxyl of the ribitol, forming a sulfur bridge bond by taking sodium sulfide as a nucleophilic reagent to obtain benzyl-protected thiosugar, oxidizing a thioether bond into sulfoxide, rearranging to obtain acetoxy thioether, and carrying out debenzylation reaction and hydroxybenzoylation reaction to obtain the high-purity acetoxy thioether. According to the present invention, the multi-step intermediate reaction only needs simple purification, the key intermediate can be obtained through recrystallization, the method is simple, the yield is high, the amplification production is convenient, and the obtained 4 '-thiosugar as the basic sugar can participate in the reaction with a variety of basic groups to form the sulfur-containing nucleoside so as to provide the good foundation for the subsequent drug development or activity screening.

This invention discloses a pullulanase mutant with enhanced catalytic activity against highly branched dextrin substrates, its construction method, and its applications, belonging to the fields of enzyme engineering and biotechnology. This invention obtains two mutants, D139A and D139E, by site-directed mutagenesis of the pullulanase derived from Klebsiella pneumoniae at position 139 aspartic acid residue. Compared with the wild-type enzyme, both mutants maintain high hydrolytic activity against pullulan polysaccharides while significantly improving hydrolytic activity against dextrin substrates with high α-1,6 glycosidic bond content. Specifically, the hydrolytic activity against dextrin substrates with 6% and 10% α-1,6 bond content is increased by up to 242% and 110%, respectively. The pullulanase mutants obtained in this invention exhibit excellent catalytic performance in the enzymatic debranching reaction of highly branched dextrin substrates, showing promising application prospects in starch deep processing and related biomanufacturing fields.

The present invention relates to use of an enzyme that cleaves both alpha- and beta-1,4-glycosidic bonds and, more particularly, the present invention provides α-L-fucosidase which has α-1,4-glucosidase and β-1,4-galactosidase activities and thus is capable of producing glucose and / or galactose, which are monosaccharides, from non-fucosylated saccharides. The enzyme has transglycosylation activity and thus produces maltooligosaccharides having a higher degree of polymerization than maltooligosaccharides used as a substrate, thereby being applicable to the development of high-value-added new materials in the food industry.