(1) Acetyl CoA exerted a dose-dependent inhibition of rat liver pyruvate kinase and glucokinase activities and also of muscle pyruvate kinase. The inhibitory effects were dependent on the length of preincubation time and there was no marked change in the affinity of the inhibited enzymes to their respective substrates. (2) Acetyl CoA, in the concentration range in which it was inhibitory to the glycolytic enzymes, did not inhibit liver hexokinase, phosphofructokinase, and lactate dehydrogenase. (3) Phosphoenolpyruvate exerted a progressive inhibition on liver glucokinase which was dependent on the length of preincubation time and it did not change the affinity of this enzyme to glucose. Under the same conditions phosphofructokinase was not inhibited. (4) Acetyl CoA might be able to exert a control on regulation of rate and direction of hepatic carbohydrate metabolism through the following effects. Acetyl CoA might provide a rapid mechanism for (1) activating the gluconeogenic enzyme, pyruvate carboxylase; (2) preventing the recycling of phosphoenolpyruvate by inhibiting the glycolytic enzyme, pyruvate kinase; (3) blocking the initiation of glycolysis by inhibiting the activity of glucokinase.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)