387 results about "Mutant enzyme" patented technology

The invention discloses a 7beta-hydroxyl sterol dehydrogenase mutant which is obtained by protein engineering and of which coenzyme preference is changed, a coding gene of the 7beta-hydroxyl sterol dehydrogenase mutant, a recombinant expression vector and a recombinant expression transformant which contain a sequence of the gene, a preparation method of a recombinant mutant enzyme preparation, andapplication of the recombinant mutant enzyme preparation to preparation of ursodeoxycholic acid. By co-enzyme regeneration of enzymic coupling, the recombinant mutant enzyme preparation disclosed bythe invention can efficiently utilize relatively cheap oxidized coenzyme I (NAD+) instead of very expensive oxidized coenzyme II (NADP+); asymmetric reduction of catalytic 7-hydroxyl lithocholic acideffectively reduces production cost; moreover, the recombinant mutant enzyme preparation has the advantages of simplicity for operation, mild reaction condition, environmental-friendliness, high yieldand the like, and has a good application prospect in preparation of ursodeoxycholic acid by epimerization of chenodesoxycholic acid.

The present invention relates to a novel endoglycoceramidase whose hydrolytic activity has been substantially reduced or eliminated, such that the enzyme is useful for synthesis of glycolipids from a monosaccharide or oligosaccharide and a ceramide. More specifically, the endoglycoceramidase is a mutant version of a naturally occurring endoglycoceramidase, preferably comprising a mutation within the active site or the nucleophilic site of the enzyme and more preferably comprising a substitution mutation of the Glu residue within the active site or the nucleophilic site. Also disclosed are a method for generating the mutant endoglycoceramidase and a method for enzymatically synthesizing glycolipids using this mutant enzyme.

The invention discloses an exo-inulinase mutant MutDR121EH9 with improved low-temperature activity, which has an amino acid sequence as shown in SEQ ID NO.1; the thermal activity and the thermal stability of the mutant MutDR121EH9 are changed, so that the mutant MutDR121EH9 has higher activity at low temperature, the thermal stability is reduced and the low-temperature activity is increased, and the use amount of enzyme is reduced or the reaction time is shortened during a low-temperature reaction; meanwhile, the degraded thermal stability makes the enzyme reaction process to be controlled through thermal treatment, wherein optimal temperature of the wild enzyme InuAMN8 is 35 DEG C, and the optimal temperature of the mutant enzyme MutDR121EH9 is 20 DEG C; after treatment at 50 DEG C, the enzyme activity of the wild enzyme InuAMN8 keeps 81% or above, and the enzyme activity of the mutant enzyme MutDR121EH9 is reduced from 32% to 14%. The mutant MutDR121EH9 disclosed by the invention can be applied to the industries of food, wine brewing, washing and the like.

The invention provides a 68th and 109th double mutant enzyme of D-psicose 3-epimerase and an application thereof, and belongs to the technical field of enzyme genetic engineering. The invention discloses the mutant enzyme Y68I / G109P which is obtained by using the D-psicose 3-epimerase (called DPE enzyme for short) derived from clostridium bolteae ATCCBAA-613 as a parent and utilizing a gene mutation technology for respectively replacing 68th tyrosine Tyr and 109th glycine Gly with isoleucine Ile and praline Pro. The heat stability and catalytic activity of the mutant enzyme Y68I / G109P are improved, therefore, the mutant enzyme Y68I / G109P has important industrial application value.

The invention relates to the technical field of gene engineering and protein modification, and discloses a low-temperature exoinulinase mutant MutDL121EK5 with improved low-temperature adaptability and application thereof, the amino acid sequence of the mutant MutDL121EK5 is obtained by replacing DAAPL from the 121st site to the 125th site of wild exoinulinase InuAMN8 with five amino acids EEDRK, and the sequence of the MutDL121EK5 is shown as SEQ ID NO.1. Compared with a wild enzyme InuAMN8, the mutant enzyme MutDL121EK5 has the advantages that the low-temperature activity is improved, the mutant enzyme MutDL121EK5 is more easily subjected to thermal denaturation, the improvement of the low-temperature activity is beneficial to reducing the dosage of the enzyme or shortening the reaction time during low-temperature reaction, and the easy thermal denaturation is beneficial to controlling the reaction process of the enzyme through thermal treatment. The low-temperature exoinulinase mutant MutDL121EK5 disclosed by the invention can be applied to the industries of food, wine brewing, washing and the like.

The invention discloses a glutamate decarboxylase mutant improving enzyme activity and an establishment method thereof, and belongs to the field of gene engineering. On the basis of an amino acid shown as SEQ ID NO.1, a 172 tyrosine is mutated to form cysteine. The obtained mutant is expressed in colibacillus, after being fermented for 24h in a shake flask, the enzyme activity is 28.6U / mL, the mutant enzyme activity is improved by 81 percent, compared with the original enzyme, the substrate affinity is reduced by 53 percent, the enzyme activity is improved by 83 percent, and the half-time period of the enzyme at 35 DEG C is increased from 16h to 24h. The recombinase is expressed in the colibacillus, and the glutamic acid is converted in a total cell manner for 18h to obtain 283.8g / L gamma-aminobutyric acid; the recombinase is expressed in glutamic acid coryneform bacteria, the glutamic acid is converted for 18h in a total cell manner to obtain 126.7g / L gamma-aminobutyric acid. The result shows that the 172 amino acid residue can severely influence the catalytic effect and stability of the enzyme, a foundation is set for researching the catalytic mechanism of the enzyme, and the industrial application potential of the enzyme is improved.