Abstract
1. Heterogeneity of malate dehydrogenase (MDH) activities was proved by electrophoresis on cellulose acetate of rat and human tissue homogenates. Two or more separable forms of MDH activities were found in these tissues. Each tissue exhibited a similar distribution of MDH activities.
2. The supernatant MDH showed a band of relatively less cathodic mobility (MDH 1), but the mitochondrial MDH (MDH 2) was found to be far more mobile, migrating toward the cathode. However, two MDH bands were observed in both fractions.
3. The acetone powder extracts showed also the two MDH activities.
4. The enzymes isolated from rat liver extracts were easely inhibited by heating, trypsin and oxaloacetate according to the staining methods.
5. It was concluded that the increased serum MDH following experimental liver damage in rats is mainly the form of MDH 1.
