The stereochemical course of reactions catalysed by Escherichia coli glutamic acid decarboxylase

Abstract

Esherischia coli glutamic acid decrboxylase reprotonates the quinoid intermediate derived from (2S)-glutamic acid on the 4′-Si-face of the coenzyme in an abortive transamination reaction, intorduces the 3-pro-R hydrogen of β-alanine during the decarboxylation of (2S)-aspartic acid and removes the 1-pro-R hydrogen of N^4′-(2-phosphoethyl)-pyridoxamine 5′-phosphate in a reactivation reaction; the results indicate that the distal binding groups of substrates and inhibitors occupy similar positions at the active site on the 3′-phenolic group side of the coenzyme.