Purification and Properties of the Pyruvate Kinase Isoenzymes Type L and M2from Chicken Liver

Abstract

A procedure for the simultaneous purification of both isoenzymes of pyruvate kinase (type M2 and L) from chicken liver was worked out. Each isoenzyme produces a single band in dodecylsulfate gel electrophoresis. Each had a MW of 190,000 and contained 4 apparently identical subunits of Mr [ fraction in exchange phase] = 50,000. The isoenzymes differ in their isoelectric points (type L; 6.3; type M2: 8.3) and their kinetic behavior. Pyruvate kinase EC - 2.7.1.40 type L had an S-shaped phosphoenolpyruvate saturation curve (K0.5 [half rate constant] = 0.79 mM) which was transformed into an hyperbola in the presence of fructose 1,6-biphosphate, while type M2 had a phosphoenolpyruvate saturation curve of the Michaelis-Menten type (K0.5 = 0.2 mM). Antibodies against pyruvate kinase type L from chicken liver inactivated type L from rat and partially inactivated type M2 from chicken and rat; but the antibodies against type L did not react with type M1 from chicken breast muscle. It was therefore concluded that avian liver contained pyruvate kinases type M2 and L as the mammalian liver does.