REGULATION OF PYRUVATE-KINASE (PK) FROM THE VENTRICLE THE LAND SNAIL HELIX-LUCORUM L DURING EARLY AND PROLONGED ESTIVATION AND HIBERNATION

The kinetic properties of pyruvate kinase (PK) from the ventricles of early and prolonged estivated and hibernated land snails, Helix lucoru m, were studied. The kinetic properties of PK from the ventricles of s nails acclimated to cold for 4 days and 2 months were also determined. Short estivation (4 days) converted the PK to a less active form, pos sibly via enzyme phosphorylation. After 2 months of estivation, PK exh ibited kinetic properties similar to control enzyme, except that the V -max increased about 2-fold, indicating metabolic reorganization. Duri ng early and prolonged hibernation, the kinetic properties of PK did n ot change significantly. The results indicate that low temperature and low pH may be the main modulators of enzyme activity in the ventricle of H. lucorum during hibernation.