Time-course of covalent modification of pyruvate kinase during anaerobiosis in the mantle muscle and the hepatopancreas of the limpet Patella caerulea (L)

Abstract

The changes in some kinetic properties of pyruvate kinase from the mantle muscle and the hepatopancreas of Patella caerulea, over a time-course of 16 or 8 h of acute hypoxia were studied. Up to the second hour of anaerobiosis PK exhibited changes of the kinetic properties in the direction of activation, whereas in the late stages of anaerobiosis in both tissues examined these changes occurred in the direction of inactivation. Although PKs from these tissues seemed to be regulated in a similar pattern during the early stages of anaerobiosis, they exhibited different kinetic properties under both normoxic and hypoxic conditions. Two forms of PK were found to be present in both the mantle muscle and the hepatopancreas of P. caerulea with different kinetic properties. The ratio of the enzyme units distributed between the two forms of PK (designated peak I and peak II) was varied during anaerobiosis indicating that the two forms of PK are interconvertible.