Some Lactobacillus L-lactate dehydrogenases exhibit comparable catalytic activities for pyruvate and oxaloacetate

The nonallosteric and allosteric L-lactate dehydrogenases of Lactobacillus pentosus and L. casei, respectively, exhibited broad substrate specificitie s, giving virtually the same maximal reaction velocity and substrate K-m va lues for pyruvate and oxaloacetate. Replacement of Pro101 with Asn reduced the activity of the L. pentosus enzyme toward these alternative substrates to a greater extent than the activity toward pyruvate.