Identification of two distinct lactate dehydrogenases in Rhodospirillum rubrum

The activities of pyridine nucleotide-independent d- and l-lactate dehydrogenases were detected in membranes from Rhodospirillum rubrum grown under aerobic and phototrophic conditions. Crossed immunoelectrophoretic analysis revealed two antigenically distinct enzymes that were further distinguished by specificity for d- and l-stereoisomers of lactate and by the sensitivity of the d-lactate dehydrogenase to inhibition by oxamate and oxalate.