Modification of the proteolytic digestibility of Neurospora pyruvate kinase by substrates and allosteric ligands.

Abstract

Neurospora pyruvate kinase was protected by the substrates PEP and ADP and an allosteric effector FDP against inactivation by pronase. Alteration of proteolysis rates in the presence of these ligands is interpreted to be due to the existence of distinct conformational states. Protein fluorescence of native pyruvate kinase was quenched by the allosteric effector to an extent of about 50%. Fluorescence behavior of the enzyme in the presence of different ligands was consistent with the conclusions of proteolysis experiments.