Meso-alpha,epsilon-diaminopimelate D-dehydrogenase: distribution and the reaction product

Abstract

A high activity of meso-.alpha.,.epsilon.-diaminopimelate dehydrogenase was found in extracts of Bacillus sphaericus, Brevibacterium sp., Corynebacterium glutamicum and Proteus vulgaris among bacteria tested. B. sphaericus IFO 3525, where the enzyme is most abundant, was chosen to study the enzyme reaction. The enzyme was not induced by adding meso-.alpha.-.epsilon.-diaminopimelate to the growth medium. The reaction product was isolated and identified as .alpha.-amino-.epsilon.-ketopimelate by a comparison of the properties of its 2,4-dinitrophenylhydrazone with those of an authentic sample in silica gel TLC absorption, IR and proton NMR spectrometry and elemental analyses. The .alpha.-amino-.epsilon.-ketopimelate formed enzymatically was decarboxylated by H2O2 to yield L-.alpha.-aminoadipate. The amino group with D-configuration in the substrate is oxidatively deaminated; the enzyme is a D-amino acid dehydrogenase. L-.alpha.-Amino-.epsilon.-ketopimelate undergoes spontaneous dehydration to the cyclic .DELTA.1-piperideine-2,6-dicarboxylate. The enzyme reaction is reversible, and meso-.alpha.-.epsilon.-diaminopimelate was formed in the reductive amination of L-.alpha.-amino-.epsilon.-ketopimelate.