4 results about "Leucine dehydrogenase" patented technology

The present invention relates to a modified dehydrogenase, wherein one or more amino acid residues of the dehydrogenase are modified as compared to an unmodified dehydrogenase, and wherein the modified dehydrogenase has an increased ratio of leucine dehydrogenase or isoleucine dehydrogenase activity to valine dehydrogenase activity as compared to the unmodified dehydrogenase, and applications thereof.

This invention provides a leucine dehydrogenase mutant, a valine-producing strain comprising this leucine dehydrogenase mutant, and its applications. The invention designs a leucine dehydrogenase mutant with the following mutations: tyrosine (Tyr) at position 48 is mutated to serine (Ser), histidine (His) at position 127 is mutated to arginine (Arg), tyrosine (Tyr) at position 186 is mutated to phenylalanine (Phe), isoleucine (Ile) at position 256 is mutated to valine (Val), and lysine (Lys) at position 308 is mutated to arginine (Arg). These mutations are used to construct a valine-producing strain. The new strain is plasmid-free, has no growth defects, requires no induction, and exhibits advantages such as good genetic stability and high fermentation yield. It is an excellent strain capable of stably producing valine. This strain efficiently synthesizes valine de novo using glucose as a substrate, significantly increasing valine yield.

The invention relates to the technical field of agricultural biology, in particular to a method for increasing the yield of strain L-leucine, a mutant and application. According to the technical scheme, the relative activity of the leucine dehydrogenase mutants AsleudhM65L and AsleudhM65L / N69D for the activity of KIC / KIV is remarkably improved compared with that of wild leucine dehydrogenase, and after the encoding genes of the AsleudhM65L and AsleudhM65L / N69D are expressed in a recombinant strain, the yield of L-leucine is greatly improved, and the yield of L-valine is reduced.

This invention discloses a method for the enzymatic synthesis of L-aminobutyric acid (GABA), comprising the following steps: using threonine and ammonium formate as substrates, a three-enzyme combined catalytic reaction is carried out using leucine dehydrogenase, threonine deaminase, and formate dehydrogenase at a temperature of 40-55°C and a pH of 7.0-9.0 to obtain L-aminobutyric acid. The leucine dehydrogenase is the leucine dehydrogenase with the amino acid sequence shown in SEQ ID NO:1 or a mutant thereof. This invention can rapidly convert threonine to L-aminobutyric acid, yielding L-aminobutyric acid with high optical purity, thus improving economic efficiency.