Apparent inhibition of pyruvate kinase by phosphocreatine and phosphoarginine

Abstract

Addition of a non-dialysable, heat-labile and acid-precipitable factor which was not absorbed on DEAE-cellulose column, could restore the sensitivity of the chromatographed muscle pyruvate kinase from Marphysa sanguinea towards phosphocreatine inhibition. This factor, being non-specific as it acts on pyruvate kinase isozymes from different sources, demonstrated high creatine kinase activity. High concentrations of ADP, creatine or replacement of ADP with IDP/UDP or high pH abolished the inhibition indicating that the inhibition was mediated through creatine kinase by depleting ADP. Apparent inhibition of phosphocreatine was related to the relative activities of 3 intracellular enzymes-pyruvate kinase, creatine kinase and adenosine triphosphatase.