Occurrence of an Inducible NADP⁺ -Dependent D-Phenylserine Dehydrogenase in Pseudomonds syringae NK-15 Isolated from Soil

Abstract

We found an inducible NADP⁺ -dependent D-phenylserine dehy-drogenase in a soil bacterium identified as Pseudomonas syringae NK-15. The enzyme catalyzed the oxidation of the 3-hydroxyl group of D-threo-3-phenylserine to yield D-2-amino-3-keto-3-phenylpropionate, which was spontaneously decarboxylated into 2-aminoacetophenone. The enzyme had an optimum reactivity at about pH 10.4. The K_m for D-threo-3-phenylserine and NADP⁺were 0.44 mM and 29 pM, respectively.