Some kinetic properties of liver pyruvate kinase (type L).

Comparison of the properties of two forms of pyruvate kinase in rat liver and determination of their separate activities during development.

1. Two forms of hepatic pyruvate kinase, designated type L and type M, were distinguished on the basis of kinetic, chromatographic, electrophoretic and immunological criteria. They were partially purified and their properties compared with each other and with the purified enzyme from skeletal muscle. 2. In contrast with type L, the type M enzyme showed no marked evidence of co-operative interac...

Kinetic properties of rat liver pyruvate kinase at cellular concentrations of enzyme, substrates and modifiers.

Kinetic properties of rat liver pyruvate kinase type I at pH7.5 and 6.5 were studied with physiological ranges of substrates, modifiers and Mg(2+) concentrations at increasing enzyme concentrations, including the estimated cellular concentrations (approx. 0.1mg/ml). Enzyme properties appear unaffected by increased enzyme concentration if phosphoenolpyruvate, fructose 1,6-diphosphate and inhibit...

Some kinetic properties of liver pyruvate kinase (type L). II. Effect of pH on its allosteric behavior.

Type L pyruvate kinase from rat liver has been further studied. The allosteric properties of the enzyme are strongly affected by changes in the hydrogen ion concentration of the assay medium. At pH values lower than 7, the enzyme obeys Michaelis-Menten kinetics with respect to one of the substrates (phosphoenolpyruvate (PEP)) and cannot be activated by fructose 1,6-diphosphate (FDP). In additio...

Some Structural and Kinetic Aspects of L - Type Pyruvate Kinase Cooperativity

Hepatic pyruvate kinase. Regulation by glucagon, cyclic adenosine 3'-5'-monophosphate, and insulin in the perfused rat liver.

A reversible interconversion of two kinetically distinct forms of hepatic pyruvate kinase regulated by glucagon and insulin is demonstrated in the perfused rat liver. The regulation does not involve the total enzyme content of the liver, but rather results in a modulation of the substrate dependence. The forms of pyruvate kinase in liver homogenates are distinguished by measurements of the rati...