Amino acid racemase with low substrate specificity (EC 5.1.1.10) purified from Pseudomonas putida ATCC17642 catalyzes the racemization of various amino acids but not that of aromatic and acidic amino acids. However, phenylalanine and phenylglycine underwent alpha-hydrogen exchange with deuterium from the solvent when incubated with the racemase in deuterium oxide. Each enantiomer of both alpha-deuterated phenylalanine and phenylglycine was produced stereospecifically with retention of the C-2 configuration. This alpha-hydrogen exchange reaction is applicable to the production of alpha-deuterated phenylalanine and phenylglycine.