The stereoisomers of α∈-diaminopimelic acid: their distribution in nature and behaviour towards certain enzyme preparations

Abstract

Approximately equal amounts of LL- and meso-diaminopimelic acid are produced and excreted by a lysine-requiring mutant of Escherichia coli 26-26. The isolation of each isomer from the culture filtrate is described. Di-aminopimelic acid isolated from hydrolyzed Corynebacterium diptheriae is the meso isomer. Proof of isomeric form was obtained by optical rotation, paper chromatography and enzymic decarboxylation. Meso-diaminopimelic acid is decarboxylated by a partially purified preparation of diaminopimelic acid decarboxylase; the LL isomer is only slightly attacked. Both these isomers are completely decarboxylated by crude acetone-dried bacterial cells, the meso isomer being the more susceptible. The DD isomer is not decarboxylated. The diaminopimelic-acid-requiring mutant E. coli 173-25 grows equally well on the meso and LL isomers, but not on the DD isomer.