Erythrocyte pyruvate kinase (PK): the variable significance of "nucleotide specificity" in the characterization of mutant variants

Inhibition of adenylate kinase by P1,P5-di(adenosine 5') pentaphosphate in assays of erythrocyte enzyme activities requiring adenine nucleotides

P1,P5-di(adenosine 5')pentaphosphate (Ap5A) is an excellent inhibitor of human hemolysate adenylate kinase at concentrations near 2 microM and above. At ten times this concentration and in hemolysate enzyme assays under conditions described in this paper it appears not to alter reaction data in the case of hexokinase, phosphofructokinase, and phosphoglycerokinase. In the pyruvate kinase assay, very modest reductions in activity are noted, and kinetics with phosphoenolpyruvate, adenosine diphosphate (ADP), and uridine diphosphate (UDP) are unaltered.