Determining a novel NAD+-dependent amine dehydrogenase with a broad substrate range from Streptomyces virginiae IFO 12827: purification and characterization

A novel NAD+-dependent amine dehydrogenase (AMDH) was screened from serinol-assimilating microorganisms and type cultures using a serinol as a substrate. The newly found enzyme from Streptomyces virginiae IFO 12827 was strictly dependent on NAD+ or NADH, and did not require artificial electron acceptors such as phenazine methosulfate (PMS), on which all the previously reported AMDHs acted. The enzyme was purified from the cell-free extract of S. virginiae cells to homogeneity by a six-step purification procedure. The enzyme had a homodimeric structure consisting of 46 kDa subunits. It catalyzed the reversible oxidative deaminations of not only amines but also amino alcohols and amino acids. The production of 2-amino-1-propanol and aspartic acid by the reductive amination of the corresponding keto alcohol and keto acid in the presence of ammonium ions and NADH, and that of acetophenone from phenethylamine by the oxidative deamination in the presence of NAD+ were confirmed by the AMDH reactions.