[Interaction of isozymes I and II of hexokinase with a microsomal fraction of skeletal muscle of rats].

The conditions of reversible transition of hexokinase from the hyaloplasm to the rat skeletal muscle microsomal membranes were studied. The maximal absorption of the enzyme by the membranes was observed in the presence of Mg2+ and glucose at weakly alkaline values of pH. Adenyl nucleotides and glucose 6-phosphate taken at physiological concentrations at neutral and weakly acid values of pH make the effect of Mg2+ reversible.

[Kinetics behavior of isozymes I and II of rat skeletal muscle hexokinase after their binding to mitochondrial membranes].

Hexokinase from rat skeletal muscle hyaloplasm is represented by two isozymic forms I and II. The values of apparent Km (glucose) for these forms were calculated according to the Reiner method. After binding to mitochondrial membranes under effects of Mg2+ the value of V for hexokinase isozyme II is increased 3-fold, while its Km value is decreased 5 times; the properties of isozyme I remain thereby unchanged.