L-alloisocitrate dehydrogenase and oxalosuccinate decarboxylase from a Pseudomonas sp. utilizing L-alloisocitrate

Two novel enzymes, NAD⁺-linked L-alloisocitrate (erythro-L_s-isocitrate) dehydrogenase and oxalosuccinate decarboxylase, were found and purified from a strain of Pseudomonas isolated as an L-alloisocitrate utilizing bacterium. The former enzyme catalyzes a reversible oxidation-reduction between L-alloisocitrate and oxalosuccinate which favors oxalosuccinate reduction. The latter enzyme catalyzes rapid decarboxylation of oxalosuccinate to α-ketoglutarate and CO₂. Both enzymes require no metals for their activities. Complete oxidative decarboxylation of L-alloisocitrate to α-ketoglutarate occurs as a result of the sequential reactions catalyzed by these two enzymes. L-Alloisocitrate induces both enzymes in the growing pseudomonad.