One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and -Transaminase

d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and -transaminase and (2) regeneration of NAD(+) by NADH oxidase. Under the cascade reaction conditions containing 100mM isopropylamine and 1mM NAD(+), complete deracemization of 100mM dl-alanine was achieved after 24h with 95% reaction yield of d-alanine (>99% ee(D), 52% isolation yield). [GRAPHICS] .