Interaction of M1 and M2 isozymes pyruvate kinase from human tissues with phosholipids

Abstract The effect of pH and the presence of FBP on the interaction of skeletal muscle (PK-M1) and kidney or tumor meningioma (PK-M2) pyruvate kinase with the phospholipids liposomes were investigated by ultracentrifugation and steady-state kinetics and were compared with those results obtained using the bovine heart (PK-M1) isoenzyme which we previously studied. Pyruvate kinase specific activity increases upon the interaction with liposomes.The activation is specifically sensitive to presence of phosphatidylserine (PS) in liposomes. Liposomes made of phosphatidylcholine+phosphatidylserine mixture are good adsorptive systems for both human and bovine of M-type isozymes at low ionic strength. Interaction of PK-M1 with PS liposomes results in the change of V max and K m values for PEP without marked effect on Hill coefficients. Addition of PS liposomes to PK-M2 induces hyperbolic saturation curves for PEP.