Activation and inhibition of the phosphoglycerate kinase reaction by ATP.

A kinetic study for understanding how the phosphoglycerate kinase (ATP: 3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) reaction discriminates between MgATP2- and ATP-4 is presented. The results show that in contrast to MgATP2-, ATP4- is competitive with 3-phospho-D-glycerate. ATP4- binds to the free enzyme as an inhibitor. When binding to the enzyme-MgATP2- (3-phospho-D-glycerate) complex, ATP4- acts as an activator.