Rabbit lactate dehydrogenase isozymes: effect of pH on activity.

The ability of lactate dehydrogenase isozyme five from rabbit skeletal muscle to catalyze pyruvate reduction is extremely sensitive to changes of pH within the range of 6.2 to 7.8. The activity of lactate dehydrogenase isozyme one from rabbit heart is virtually unaffected by changes of pH within the same range. Isozyme five is activated by low concentrations of oxalacetate and inhibited by higher concentrations, but other substrates of the citric acid cycle have no effect.