| 主权项 |
1. A process for converting a compound of formula I which is a substrate for an amino acid dehydrogenase to a chiral amino acid of formula IIa:comprising contacting the compound of formula I with a reaction medium comprising an amino acid dehydrogenase, an ammonium ion donor selected from ammonia or an ammonium salt, a cofactor selected from NAD+/NADH or NADP+/NADPH, and a cofactor regenerating system comprising an engineered ketoreductase having at least 90% sequence identity to SEQ ID NO: 18, which has less than 5% of the activity of the amino acid dehydrogenase, with compound of formula I and a lower secondary alcohol, under conditions where the compound of formula I is converted to the chiral amino acid of formula IIa and the lower secondary alcohol is converted to a ketone, wherein R is a substituted or unsubstituted —(C1-C10)alkyl, —(C2-C6)alkenyl, —(C2-C6)alkynyl, —(C3-C8)cycloalkyl, heterocycloalkyl, aryl, or heteroaryl and wherein the said ketoreductase is capable of recycling cofactor by converting isopropanol (IPA) to acetone with an activity at least 2.0-fold greater than a reference ketoreductase of SEQ ID NO: 2. |
