16 results about "Catalytic rate" patented technology

Glycosyltransferase UGT76G1 and UGT91C1 mutants and a method for catalytic synthesis of rebaudioside A, D, and M by using same, pertaining to the technical field of biocatalytic synthesis. The glycosyltransferase UGT76G1 mutant can effectively synthesize rebaudioside A using stevioside STV as a substrate. The glycosyltransferase UGT91C1 mutant is obtained by mutation screening of wild-type glycosyltransferase UGT91C1, has higher enzyme activity and catalytic rate, and can effectively synthesize rebaudioside D using rebaudioside A as a substrate. The glycosyltransferase UGT76G1 mutant can also be obtained by mutation and subsequent screening of glycosyltransferase UGT76G1, has higher catalytic activity, and can effectively synthesize rebaudioside M using rebaudioside D and UDPG as substrates.

The invention discloses a method for preparing psicose by catalyzing fructose conversion through immobilized isomerase, and belongs to the technical field of sweeteners, the method comprises the following steps: glycosylation of DAEase enzyme, preparation of a lectin carrier, immobilization of glycosylated DAEase enzyme, and catalytic preparation of psicose; the method for immobilizing the glycosylated DAEase enzyme comprises the following steps: dispersing the glycosylated DAEase enzyme and a lectin carrier in a sodium phosphate buffer solution, stirring at room temperature for 1-1.2 hours, centrifuging to remove supernate, adding into a glutaraldehyde solution, cross-linking at room temperature for 1-1.5 hours, and freeze-drying to obtain the immobilized isomerase, according to the method disclosed by the invention, the activity of the immobilized enzyme, the conversion rate of D-fructose and the catalytic rate of DAEase are improved.

The application relates to a soluble expression vector of a steroid C14 alpha hydroxylase and a construction method and application thereof, and belongs to the technical field of biotechnology. A nucleic acid sequence coding a steroid C14 alpha hydroxylase and a nucleic acid sequence coding a soluble label maltose binding protein are expressed in a vector, the nucleic acid sequence coding the steroid C14 alpha hydroxylase is shown as SEQ ID NO. 1, and the amino acid sequence of the steroid C14 alpha hydroxylase is shown as SEQ ID NO. 2. The application establishes a soluble expression vector and a method of a fungus-derived enzyme in Escherichia coli, and provides a new idea for obtaining solubility of other CYP enzymes in the heterologous expression of Escherichia coli. The application significantly improves the electron transfer efficiency of the hydroxylation process by constructing an intramolecular hydrogen delivery system, and partially solves the problem of low overall catalytic rate caused by low electron transfer efficiency in the catalytic reaction of P450 monooxygenase.

The application discloses a glycosyltransferase UGT91C1 mutant and a method for catalyzing synthesis of rebaudioside D, and belongs to biological catalytic synthesis. The glycosyltransferase UGT91C1 mutant is any one of the following (A)-(C): A) a protein obtained by making any one or more mutations in the amino acid sequence shown in SEQ ID NO. 1: the 89th amino acid is mutated from N to Y; the 155th amino acid is mutated from M to L; the 274th amino acid is mutated from S to T; and the 361st amino acid is mutated from N to S; (B) a protein having 95% or 98% or above identity with the amino acid sequence defined in (A) and having the same function; and (C) a fusion protein obtained by connecting a tag to the end of the protein defined in (A) or (B). The glycosyltransferase UGT91C1 mutant is obtained by mutation screening from a wild-type glycosyltransferase UGT91C1, has higher enzyme activity and catalytic rate, and can efficiently synthesize rebaudioside D by taking rebaudioside A as a substrate.

The invention discloses a CDs (at) MgO2 nano composite material as well as a preparation method and application thereof, and belongs to the technical field of photocatalytic materials. The preparation process of the composite material comprises the following steps: preparing CDs (etching coal tar pitch through formic acid-hydrogen peroxide, centrifuging, dialyzing and drying), preparing a MgCl2 aqueous solution, constructing a microemulsion system, treating with ammonia water, carrying out peroxidation reaction, adjusting pH, separating and purifying, and drying and forming. The CDs and the MgO2 are proved to be effectively compounded through SEM, TEM, XRD, FT-IR, XPS, EDS and other characterization means; a photocatalytic test shows that the catalytic rate of CDs-coated MgO2 to TMB is far higher than that of pure MgO2, an enzyme kinetics test shows that the maximum catalytic rate of the compound is remarkably superior to that of MgO2, and the compound has excellent antibacterial activity to staphylococcus aureus; mechanism exploration shows that the CDs reduce the band gap of MgO2 and broaden the light response range, the CDs and MgO2 form a heterojunction to improve the charge separation efficiency, and the CDs are dominant active substances. The method is simple in process and excellent in performance, and can be widely applied to the fields of photocatalytic degradation of organic pollutants and antibiosis.

The method and device for determining the catalytic efficiency of the artificial ice nucleus material provided by the embodiments of the present disclosure comprise the following steps: determining the three-dimensional reconstruction graph and the lattice mismatch degree of the biological macromolecular multi-scale complex according to a preset first observation condition; determining the thermodynamic evaluation result based on the three-dimensional reconstruction graph, the lattice mismatch degree and a preset second observation condition; obtaining the process image of the newly generated ice crystal front surface based on a preset third observation condition; extracting the newly generated ice crystal front surface advancing contour line and the differentiated time track path from the process image according to a space reference; determining the catalytic rate order jump according to the advancing contour line and the differentiated time track path; obtaining the extreme catalytic efficiency quantitative result; realizing the analysis of the biological macromolecular multi-scale complex native hydration folding conformation; accurately positioning and quantifying the core nucleation active center; and providing the quantitative backstepping mechanism of the interface polarity and the thermodynamic nucleation potential barrier.

The present application discloses an artificial enzyme, which is prepared based on sequence modification of a natural enzyme having the activity of catalyzing the reaction of converting compound I (nicotine) into compound II (N-methyl-4-hydroxy-3-methylnicotinamide) shown as follows, and compound II (N-methyl-4-hydroxy-3-methylnicotinamide) can spontaneously hydrate to generate compound III (pseudo-oxidized nicotine), or the natural enzyme is nicotine dehydrogenase; the modification includes replacing at least one of the amino acids that hinder the release of the product with an amino acid with a smaller side chain. The artificial enzyme has a higher catalytic rate on the substrate than the natural enzyme, and is very promising in the preparation of drugs for treating nicotine addiction.

This invention provides a mutant of heme iron cytochrome P450 enzyme with enhanced electrocatalytic rate and its application. By performing site-directed mutagenesis on the heme iron cytochrome enzyme with the amino acid sequence shown in SEQ ID NO:1 as the parent, leucine at position 82 of SEQ ID NO:1 is mutated to glutamine, phenylalanine at position 167 is mutated to methionine, or valine at position 280 is mutated to threonine, a mutant with enhanced electrocatalytic rate is obtained, thereby solving the technical problem of low electrocatalytic rate of heme iron cytochrome enzyme in the prior art.

Tobacco etch virus protease (TEV) is one of the most widely used proteases in biotechnology because of its exquisite sequence-specificity. A limitation of TEV is its slow catalytic rate, which limits product generation and therefore signal output. Provided is a generalizable yeast-based platform for directed evolution of protease catalytic properties. Protease activity is determined via proteolytic release of a membrane-anchored transcription factor, and access to TEV's cleavage site is temporally regulated using a photosensory LOV domain. By gradually decreasing light exposure time, faster variants of TEV were selected over multiple rounds of selection. The mutant TEV proteases and the directed evolution platform are useful in a wide range of biotechnology applications, such as FLARE and SPARK tools.

The invention discloses a method for detecting micro RNA (Ribonucleic Acid) by using chemically modified multi-component deoxyribozyme and application of the method, and belongs to the field of molecular diagnosis and biosensing. Heterogeneous nucleic acid modification is introduced into a catalytic core region of a deoxyribozyme molecule, and locked nucleic acid modification is introduced into a target binding arm region; heterogeneous nucleic acid modification is used for enhancing the conformational stability and catalytic rate of the catalytic core, and locked nucleic acid modification is used for improving the recognition affinity and specificity of the target binding arm and the target miRNA. The method has the advantages that the detection reaction is realized under the enzyme-free, isothermal and one-pot conditions, and the detection efficiency and sensitivity are remarkably improved. The catalytic rate is increased by 6.5 times after XNA modification is introduced, the overall catalytic efficiency is increased to 760 times after LNA modification is introduced, and the detection sensitivity is increased to 2 pM. The method is flexible in structural design, simple and convenient to operate, high in specificity and suitable for application scenes such as field detection and liquid biopsy, and has a good industrialization prospect.

The invention belongs to the technical field of bioengineering and enzyme engineering, and particularly relates to a pyranose oxidase mutant and application thereof in glucose detection. The invention discloses a pyranose oxidase mutant. The mutant is obtained by mutating the 155th site of an amino acid sequence as shown in SEQ ID NO. 2; according to the mutant, glutamine at the 155th position is mutated into threonine, alanine or glycine. Compared with a wild type, the mutant disclosed by the invention has the advantages that the affinity to interferents such as 1, 5-anhydrous-D-glucitol and the like is remarkably reduced while a high catalytic rate is reserved. The mutant provided by the invention has good linear response in a glucose concentration range of 0.02-5 mM, and especially can accurately detect low-concentration glucose in the presence of interference of physiological concentration 1, 5-AG, so that the problem of false positive caused by interferents in the prior art is effectively solved. The mutant enzyme can be widely applied to the fields of enzymatic biosensors, saliva and tear noninvasive blood glucose monitoring and the like.

The present application relates to a kind of synthesis of rhodium catalyst containing phosphine porous organic polymer / molecular sieve composite carrier and its catalytic tandem olefin hydroformylation- acetalization reaction. Specifically, it is obtained by polymerization reaction of monomer and molecular sieve mixture to obtain composite carrier, and further loaded with rhodium to obtain the corresponding catalyst. The catalyst can catalyze olefin, H2 / CO and organic alcohol one-pot preparation of acetal, belonging to the technical field of organic chemistry. The present application provides high catalytic rate, wide substrate applicability, high regioselectivity and recycling in the catalytic tandem hydroformylation / acetalization reaction.

A polymer brush composed of statistical copolymers of hydrophilic and hydrophobic monomers for enzyme immobilization. The heterogeneous polymer brushes stabilized four different lipases against high temperatures. Notably, the statistical copolymers stabilized the four lipases to a greater extent than a homopolymer brush. Additionally, in the case of Rhizomucor miehei lipase, statistical copolymers stabilized the enzyme to a greater extent than homopolymers of either hydrophilic or hydrophobic monomers. The resulting increase in high-temperature stability enabled significant improvements in catalytic rates by operating reactions at elevated temperatures, which is desirable for enzyme catalysis and sensing applications. Additionally, stabilization against elevated temperatures implies stabilization against non-aqueous solvents, which is of critical importance to numerous applications of biocatalysts.

The present application relates to a kind of metal modified MCM-22 molecular sieve catalytic synthesis of p-xylene method, belong to chemical catalysis technical field.The method with 2,5-dimethylfuran and acrylic acid as reactant, with metal modified MCM-22 molecular sieve as catalyst, in magnetic stirring tank, initial reaction pressure is normal pressure, reaction temperature is 150 ℃~190 ℃;Reaction time is 3h~10h, nitrogen is as the condition of protective gas is carried out.The metal modified MCM-22 molecular sieve obtained in the present application has high external specific surface characteristics, by the method of physical mixing and re-calcination, realize the synergistic effect of L acid site on metal oxide and MCM-22 surface B acid site, balance B acid, L acid site catalytic rate, speed up total reaction rate.99%2,5-DMF conversion rate and 98%PX selectivity can be obtained after reaction temperature is 150 ℃, reaction 10h.

The invention provides a KpADH alcohol dehydrogenase mutant and application of the KpADH alcohol dehydrogenase mutant in syringol synthesis, under the condition that a recombinant expression vector pET28a-KpADH is used as a template, the 165 site and the 231 site of KpADH alcohol dehydrogenase with the amino acid sequence as shown in SEQ ID NO.1 are subjected to single-point or double mutation, and the KpADH alcohol dehydrogenase mutant is obtained. The mutant shows an enhanced catalytic rate. Wherein the KpADH alcohol dehydrogenase mutant C165F-V231D whole-cell catalyst can be used for reducing 20 mM of syringaldehyde into the syringyl alcohol within 24 hours, and the yield reaches 92.1 percent.

The application discloses a synthesis method of a benzene pyrimidyl sulfonamide intermediate 2-chloro-4-fluorobenzoic acid, and specifically comprises the following steps: 1) taking 2-chloro-4-fluoroaniline as raw material, performing a diazotization reaction in the presence of sulfuric acid and sodium nitrite to generate aniline diazonium salt; 2) the diazonium salt reacts with acetaldoxime in the presence of a composite catalyst under a weak acid environment to generate 2-chloro-4-fluoroacetophenone oxime; 3) 2-chloro-4-fluoroacetophenone oxime is hydrolyzed by refluxing in a hydrochloric acid solution to generate 2-chloro-4-fluoroacetophenone; 4) 2-chloro-4-fluoroacetophenone is subjected to an oxidation reaction with sodium hypochlorite under alkaline conditions, and then is hydrolyzed in concentrated hydrochloric acid to generate 2-chloro-4-fluorobenzoic acid. The application selects 2-chloro-4-fluoroaniline as raw material, which is cheap and easy to obtain, so that the cost is reduced, and the reaction is performed by using a limited composite catalyst, so that the catalytic rate is fast, the reaction time is short, and the selectivity is high.