Stereochemical course of the decarboxylation of (S)-glutamic acid by glutamate decarboxylase from Escherichia coli (E.C. 4.1.1.15)

Decarboxylation of (S)-glutamic acid (1) in 2H2O, catalysed by glutamate decarboxylase from Escherichia coli (E.C.4.1.1.15), afforded 4-[4-2H]aminobutyric acid (2b). (+)-(S)-4-[4- 2H]aminobutyric acid (2c) was synthesized and the 1H n.m.r. spectrum of the (1S,4R)-O-camphanoylamide of its methyl ester compared with the same derivative of (2b) in the presence of the shift reagent [Eu(dpm)3]. It was shown that (2b) is in the (R) configuration and that glutamate decarboxylase catalyses the decarboxylation of (1) with retention of configuration.