Regulation of gluconeogenesis and glycolysis: Studies of mechanisms controlling enzyme activity

Various regulatory mechanisms functioning at the enzyme activity and enzyme biosynthetic level in carbohydrate metabolism were explored. The regulatory influences operate on receptor sites on the enzyme molecules and on the enzyme-forming systems. These enzymatic control mechanisms were examined as the basis for rapid and chronic regulation of gluconeogenesis and glycolysis by hormones and regulatory signal molecules. This work presented the effects of NADH, free fatty acids, and other compounds on strategic enzymes of liver carbohydrate metabolism. The selective action of free fatty acids was characterized in terms of inhibition of key enzymes of glycolysis, and the direct oxidative pathway, and of certain enzymes in the Krebs cycle. Since liver pyruvate kinase is pivotal in the regulation of gluconeogenesis and glycolysis, detailed attention was given to the effects of fructose 1,6-diphosphate, ATP, ADP, NADH, magnesium, free fatty acids, and other regulatory molecules on this enzyme.