Comparison of properties of malate dehydrogenase isoenzymes from hare and rabbit hearts

The hare heart mitochondrial malate dehydrogenase (mMDH) was established to have a much higher electrophoretic mobility than the corresponding enzyme from the rabbit heart. Differences of kinetic properties of both mMDH and cytoplasmic malate dehydrogenase (cMDH) from these two sources were shown. The hare heart mMDH and cMDH isoenzymes have a higher affinity to malate (in direct reaction) and oxaloacetate and NADH (in reverse reaction), i.e., they have lower K _M values in comparison with the isoenzymes from the rabbit heart. Malate dehydrogenase seems to operate more effectively in the hare heart, which might be important in adaptive and evolutionary aspects.