Stereochemistry of Decarboxylation Reactions Catalyzed by a Constitutive Aromatic L-Amino Acid Decarboxylase

Abstract

The stereochemistry of the decarboxylation reaction catalyzed by an aromatic L-amino acid decarboxylase, purified from Micrococcus percitreus, was studied using stereospecifically deuterium labelled phenylalanine (Phe). The ¹H NMR spectrum of [1, 2-²H₂]-β-phenethylamine enzymatically derived from (2S, 3R)-[3-²H]-Phe in ²H₂O was compared with that of [l-²H]- β-phenethylamine from unlabelled Phe in ²H₂O. The results clearly indicate that the decarboxylation reaction of this enzyme proceeds exclusively through a course in which the configuration at C-2 of Phe is retained.