EXCHANGE OF THE VALINE-2-H IN THE BIOSYNTHESIS OF L-DELTA-(ALPHA-AMINOADIPOYL)-L-CYSTEINYL-D-VALINE

Incubation of [2-H-2]-valine with purified ACV synthetase from both Cephalosporium acremonium and Streptomyces clavuligerus produced L-delta-(alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV), determined by the essentially complete (>95%) loss of deuterium from the alpha position of the incorporated valine. Incubations with deuterium oxide/water as solvent produced ACV with significant incorporation of deuterium into the valinyl residue. These observations confirm the prior proposal that a single multifunctional enzyme is responsible for both the formation of the peptide bonds of ACV and the epimerisation of the valinyl residue.