Abstract: An R-3-aminobutyric acid preparation method with high efficiency and high stereoselectivity. The method comprises using aspartase with stereoisomerization catalytic activity derived from Escherichia coli to efficiently convert butenoic acid into R-3-aminobutyric acid. After only 24 h of reaction, the conversion rate is as high as ?98%, and the ee value is ?99.9%. The conversion efficiency is greatly improved, the reaction time is shortened, and the production costs are reduced. The method features a high yield, a high conversion rate, low costs, a short production cycle, a simple process, ease of enlargement, suitability for mass production and the like.

Abstract: The present invention discloses a genetically engineered bacteria, which is E. coli integrated with lysogenic ?DE3, and lacZ gene is completely inactivated, but does not affect exogenous protein expression of the genetically engineered bacteria. The present invention also discloses a method for culturing the genetically engineered bacteria, and a method for preparing human milk oligosaccharides using the same, and use of the genetically engineered bacteria. The genetically engineered bacteria of the present invention can efficiently produce human milk oligosaccharides, such as 2?-fucosyllactose, and have wide industrial application prospects.

Abstract: The invention discloses a genetically engineered bacterium and a method for preparing a fucosylated oligosaccharide using the same. The method includes: transferring a fucosyl group of a donor to an oligosaccharide receptor by a fucosyltransferase heterologously expressed in a genetically engineered bacterium; wherein the donor is a nucleotide-activated donor, the fucosyltransferase has ?-1,2-fucosyltransferase activity; wherein, the fucosyltransferase is selected from one or more of the enzymes corresponding to NCBI Accession Numbers WP_109047124.1, RTL12957.1, MBP7103497.1, WP_120175093.1, RYE22506.1, WP_140393075.1 and HJB91111.1. The preparation method of the invention has high yield, greatly improved substrate conversion rate and product conversion rate, and has the potential to be applied to industrial production.

Abstract: Disclosed in the present invention is a fluoroacetate dehalogenase mutant, a sequence of the fluoroacetate dehalogenase mutant comprising a mutated sequence having an amino acid residue H at position 155 and/or an amino acid residue W at position 156, as shown in SEQ ID NO: 1; the fluoroacetate dehalogenase mutant has activity catalyzing bromination of a substrate, particularly a 2-bromobutyric acid substrate. Also provided in the present invention is an application of said fluoroacetate dehalogenase mutant in the preparation of (R)-2-bromobutyric acid and/or (R)-2-hydroxybutyric acid. When using the fluoroacetate dehalogenase mutant of the present invention to prepare (R)-2-bromobutyric acid, production costs are low and stereoselectivity is high, facilitating industrialized production.

Abstract: Use of a stereoselective transaminase in the asymmetric synthesis of a chiral amine. In particular, provided is use of a polypeptide in the production of a chiral amine or a downstream product using a chiral amine as a precursor. Further provided is a method for producing a chiral amine, comprising culturing a strain expressing the polypeptide so as to obtain a chiral amine. Further provided are novel prochiral compounds, a chiral amine production strain and a method for constructing the chiral amine production strain. The stereoselective transaminase has a broad substrate spectrum and thus has a broad application potential in the preparation of a chiral amine.

Abstract: Disclosed in the present invention is an L-glutamate dehydrogenase mutant, the sequence of the L-glutamate dehydrogenase mutant being a sequence in which amino acid residue A at position 175 in SEQ ID NO: 1 is mutated to be G, and amino acid residue V at position 386 is mutated to be an amino acid residue having less steric hindrance. Further disclosed in the present invention is an application of the described L-amino acid dehydrogenase mutant in the preparation of L-glufosinate-ammonium or a salt thereof. When the L-glutamate dehydrogenase mutant of the present invention is used to prepare L-glufosinate-ammonium or a salt thereof, compared to an L-glutamate dehydrogenase mutant in which only position 175 or 386 is mutated, the specific enzyme activity is higher. Therefore, the action efficiency of the enzyme is improved, reaction costs are reduced, and industrial production is facilitated.

Abstract: Provided are an L-glutamate dehydrogenase mutant and an application thereof, the mutant mutating the amino acid residue A at position 166 and/or the amino acid residue V at position 376 shown in SEQ ID NO. 1 into a hydrophilic or small sterically hindered amino acid residue, the application performing an amination reaction of 2-oxo-4-(hydroxymethylphosphinyl)butyrate in the presence of an L-amino acid dehydrogenase mutant, an inorganic amino donor, and a reduced coenzyme NADPH, and performing an acidification reaction on the obtained L-glufosinate salt to obtain L-glufosinate. Compared to wild L-glutamate dehydrogenase, the present L-glutamate dehydrogenase mutant has a higher concentration of substrates that can be catalysed when preparing L-glufosinate, thereby increasing the efficiency of the action of the enzyme and reducing reaction costs.

Abstract: Use of a stereoselective transaminase in the asymmetric synthesis of a chiral amine. In particular, provided is use of a polypeptide in the production of a chiral amine or a downstream product using a chiral amine as a precursor. Further provided is a method for producing a chiral amine, comprising culturing a strain expressing the polypeptide so as to obtain a chiral amine. Further provided are novel prochiral compounds, a chiral amine production strain and a method for constructing the chiral amine production strain. The stereoselective transaminase has a broad substrate spectrum and thus has a broad application potential in the preparation of a chiral amine.

Abstract: Disclosed in the present invention is an L-glutamate dehydrogenase mutant, the sequence of the L-glutamate dehydrogenase mutant being a sequence in which amino acid residue A at position 175 in SEQ ID NO: 1 is mutated to be G, and amino acid residue V at position 386 is mutated to be an amino acid residue having less steric hindrance. Further disclosed in the present invention is an application of the described L-amino acid dehydrogenase mutant in the preparation of L-glufosinate-ammonium or a salt thereof. When the L-glutamate dehydrogenase mutant of the present invention is used to prepare L-glufosinate-ammonium or a salt thereof, compared to an L-glutamate dehydrogenase mutant in which only position 175 or 386 is mutated, the specific enzyme activity is higher. Therefore, the action efficiency of the enzyme is improved, reaction costs are reduced, and industrial production is facilitated.

Abstract: Provided is a D-amino acid oxidative enzyme mutant. The sequence of the mutant comprises a sequence by mutating the 54th amino acid residue N, the 58th amino acid residue F, the 211th amino acid residue C, and the 213th amino acid residue M of the sequence shown in SEQ ID NO:1 or the sequence having at least 76% identity with SEQ ID NO:1. The D-amino acid oxidative enzyme mutant has a higher enzyme activity, enzyme activity stability and/or ammonium resistance than a mild D-amino acid oxidative enzyme mutant. Also provided is an application of the D-amino acid oxidative enzyme mutant in preparing 2-oxo-4-(hydroxymethylphosphinyl)butyric acid.

Abstract: Provided are an L-glutamate dehydrogenase mutant and an application thereof, the mutant mutating the amino acid residue A at position 166 and/or the amino acid residue V at position 376 shown in SEQ ID NO. 1 into a hydrophilic or small sterically hindered amino acid residue, the application performing an amination reaction of 2-oxo-4-(hydroxymethylphosphinyl)butyrate in the presence of an L-amino acid dehydrogenase mutant, an inorganic amino donor, and a reduced coenzyme NADPH, and performing an acidification reaction on the obtained L-glufosinate salt to obtain L-glufosinate. Compared to wild L-glutamate dehydrogenase, the present L-glutamate dehydrogenase mutant has a higher concentration of substrates that can be catalysed when preparing L-glufosinate, thereby increasing the efficiency of the action of the enzyme and reducing reaction costs.

Abstract: Provided is use of immobilized transaminase in preparation of sitagliptin and/or (R)-3-amino-1-morpholine-4-(2,4,5-trifluorophenyl)-1-butanone. The immobilized transaminase comprises resin and a transaminase mutant, the amino acid sequence of the transaminase mutant is as shown in SEQ ID NO: 3 or SEQ ID NO: 7. Also provided is an immobilized transaminase, a transaminase mutant, a preparation method therefor and use thereof. The enzyme activity of the transaminase mutant in the catalysis of a ketoamide substrate is high, and the enzyme activity is still high after the transaminase mutant is prepared into the immobilized transaminase.

Abstract: Use of a stereoselective transaminase in the asymmetric synthesis of a chiral amine. In particular, provided is use of a polypeptide in the production of a chiral amine or a downstream product using a chiral amine as a precursor. Further provided is a method for producing a chiral amine, comprising culturing a strain expressing the polypeptide so as to obtain a chiral amine. Further provided are a chiral amine production strain and a method for constructing the chiral amine production strain. The stereoselective transaminase has a broad substrate spectrum and thus has a broad application potential in the preparation of a chiral amine.

Abstract: The invention provides a highly active S-cyanohydrin lyase obtained by mutating an amino acid residue at position 103 of a wild-type cassava S-cyanohydrin lyase. The mutation can significantly increase an expression of a mutant enzyme in E. coli and does not require a decrease in temperature when induced. Further mutations at position 128 and other sites were performed to obtain mutants with increased catalytic activity.

Abstract: An R-3-aminobutyric acid preparation method with high efficiency and high stereoselectivity. The method comprises using aspartase with stereoisomerization catalytic activity derived from Escherichia coli to efficiently convert butenoic acid into R-3-aminobutyric acid. After only 24 h of reaction, the conversion rate is as high as ?98%, and the ee value is ?99.9%. The conversion efficiency is greatly improved, the reaction time is shortened, and the production costs are reduced. The method features a high yield, a high conversion rate, low costs, a short production cycle, a simple process, ease of enlargement, suitability for mass production and the like.

Abstract: Provided is a D-amino acid oxidative enzyme mutant. The sequence of the mutant comprises a sequence by mutating the 54th amino acid residue N, the 58th amino acid residue F, the 211th amino acid residue C, and the 213th amino acid residue M of the sequence shown in SEQ ID NO:1 or the sequence having at least 76% identity with SEQ ID NO:1. The D-amino acid oxidative enzyme mutant has a higher enzyme activity, enzyme activity stability and/or ammonium resistance than a mild D-amino acid oxidative enzyme mutant. Also provided is an application of the D-amino acid oxidative enzyme mutant in preparing 2-oxo-4-(hydroxymethylphosphinyl)butyric acid.

Abstract: An R-3-aminobutyric acid preparation method with high efficiency and high stereoselectivity. The method comprises using aspartase with stereoisomerization catalytic activity derived from Escherichia coli to efficiently convert butenoic acid into R-3-aminobutyric acid. After only 24 h of reaction, the conversion rate is as high as ?98%, and the ee value is ?99.9%. The conversion efficiency is greatly improved, the reaction time is shortened, and the production costs are reduced. The method features a high yield, a high conversion rate, low costs, a short production cycle, a simple process, ease of enlargement, suitability for mass production and the like.

Abstract: The invention provides a highly active S-cyanohydrin lyase obtained by mutating an amino acid residue at position 103 of a wild-type cassava S-cyanohydrin lyase. The mutation can significantly increase an expression of a mutant enzyme in E. coli and does not require a decrease in temperature when induced. Further mutations at position 128 and other sites were performed to obtain mutants with increased catalytic activity.

Abstract: Provided are an L-glutamate dehydrogenase mutant and an application thereof, the mutant mutating the amino acid residue A at position 166 and/or the amino acid residue V at position 376 shown in SEQ ID NO. 1 into a hydrophilic or small sterically hindered amino acid residue, the application performing an amination reaction of 2-oxo-4-(hydroxymethylphosphinyl)butyrate in the presence of an L-amino acid dehydrogenase mutant, an inorganic amino donor, and a reduced coenzyme NADPH, and performing an acidification reaction on the obtained L-glufosinate salt to obtain L-glufosinate. Compared to wild L-glutamate dehydrogenase, the present L-glutamate dehydrogenase mutant has a higher concentration of substrates that can be catalysed when preparing L-glufosinate, thereby increasing the efficiency of the action of the enzyme and reducing reaction costs.

Abstract: An R-3-aminobutyric acid preparation method with high efficiency and high stereoselectivity. The method comprises using aspartase with stereoisomerization catalytic activity derived from Escherichia coli to efficiently convert butenoic acid into R-3-aminobutyric acid. After only 24 h of reaction, the conversion rate is as high as ?98%, and the ee value is ?99.9%. The conversion efficiency is greatly improved, the reaction time is shortened, and the production costs are reduced. The method features a high yield, a high conversion rate, low costs, a short production cycle, a simple process, ease of enlargement, suitability for mass production and the like.