Comparative studies of vertebrate and invertebrate pyruvate kinases

1. Electrophoretic patterns showed that among the vertebrates studied, L isozyme was present in rat and frog liver and also in rat kidney. 2. M2 is a frequent component in vertebrate tissues, giving support to the proposal that M2 is the ancestral form differentiating to other isozymes. 3. The above trend cannot simply apply to invertebrates. 4. Muscle pyruvate kinases from various animals were inhibited by the particular phosphagen present in their muscle. 5. The inhibition may have an important role in the regulation of glycolysis in muscle.