Provided is an amino acid dehydrogenase mutant. The amino acid sequence of the mutant is obtained by mutating the amino acid sequence shown in SEQ ID NO:1. The mutation includes at least one of the following mutation sites: 64th, 94th, 133rd, 137th, 148th, 168th, 173rd, 183 rd, 191st, 207th, 229th, 248th, 255th and 282nd sites; or the amino acid sequence of the amino acid dehydrogenase mutant is an amino acid sequence having the mutation sites in the mutated amino acid sequence and having a 80% or more homology with the mutated amino acid sequence. The mutant enzyme activity is more than 50 times higher than that of wild amino acid dehydrogenase, and the enzyme specificity is also correspondingly improved.

The present disclosure relates to the use of an amino acid dehydrogenase in combination with a cofactor regenerating system comprising a ketoreductase. In particular embodiments, the process can be used to prepare L-tert-leucine using a leucine dehydrogenase.

The present disclosure provides microbial organisms having decreased production of unwanted by-products (e.g, pyruvate-, CO.sub.2—, TCA-derived by-products; acetate; ethanol; and/or, alanine) to enhance carbon flux through acetyl-CoA, which can increase production of acetyl-CoA derived compounds (e.g, 1,3-BDO, MMA, and (3R)-hydroxybutyl (3R)-hydroxybutyrate, or any other acetyl-CoA derived compounds), and products made from any of these compounds. Also provided are one or more exogenous nucleic acids encoding enzymes that can decrease production of unwanted by-products (e.g, aldehyde dehydrogenase, acetyl-CoA synthase, amino acid dehydrogenase, alanine racemase, and/or citrate synthase), and/or one or more gene attenuations occurring in genes (e.g., acetolactate synthase) that result in decreased production of unwanted by-products. Various combinations of the exogenous nucleic acids and gene deletions are also provided in the present disclosure. Methods of making and using the same, including methods for culturing cells, and for the production of the various products are also provided.

Provided is an amino acid dehydrogenase mutant. The amino acid sequence of the mutant is obtained by mutating the amino acid sequence shown in SEQ ID NO:1. The mutation includes at least one of the following mutation sites: 64th, 94th, 133rd, 137th, 148th, 168th, 173rd, 183 rd, 191st, 207th, 229th, 248th, 255th and 282nd sites; or the amino acid sequence of the amino acid dehydrogenase mutant is an amino acid sequence having the mutation sites in the mutated amino acid sequence and having a 80% or more homology with the mutated amino acid sequence. The mutant enzyme activity is more than 50 times higher than that of wild amino acid dehydrogenase, and the enzyme specificity is also correspondingly improved.

An enzyme having the following characteristics (a) and (b): (a) the enzyme has an activity of reversible dehydrogenation of D-amino acids; (b) the enzyme is a hexamer of polypeptides having an amino acid sequence having 80% or greater identity to the amino acid sequence of SEQ ID NO: 2.

An enzyme has an activity of reversible dehydrogenation of D-amino acid and is a hexamer of polypeptides having an amino acid sequence that has 80% or more identity with the amino acid sequence of SEQ ID NO: 2. The amino acid sequence of the polypeptide can include one or more amino acid substitutions for one or more amino acid residues of SEQ ID NO: 2.

An enzyme having the following characteristics (a) and (b): (a) the enzyme has an activity of reversible dehydrogenation of D-amino acids; (b) the enzyme is a hexamer of polypeptides having an amino acid sequence having 80% or greater identity to the amino acid sequence of SEQ ID NO: 2.

An enzyme having the following characteristics of (a) and (b): (a) the enzyme has an activity of reversible dehydrogenation of D-amino acid; and (b) the enzyme is a hexamer of polypeptides having an amino acid sequence that has 80% or more identity with an amino acid sequence of SEQ ID NO: 2.

The present disclosure relates to the use of an amino acid dehydrogenase in combination with a cofactor regenerating system comprising a ketoreductase. In particular embodiments, the process can be used to prepare L-tert-leucine using a leucine dehydrogenase.

The present disclosure relates to the use of an amino acid dehydrogenase in combination with a cofactor regenerating system comprising a ketoreductase. In particular embodiments, the process can be used to prepare L-tert-leucine using a leucine dehydrogenase.