Influence of free Mg2+ on the kinetics of human erythrocyte phosphofructokinase.
The influence of Mg2+ on the reaction catalyzed by human erythrocyte phosphofructokinase has been investigated using kinetic methods. The catalytic activity of PFK is dependent upon the presence of Mg2+ which constitutes with ATP the true Mg-ATP2- substrate. Free Mg2+ has no influence on the affinity of the enzyme for Mg-ATP2- substrate. Erythrocyte PFK is more inhibited by ATP4- and uncomplexed citrate than it is by Mg-ATP2- and Mg-citrate. Free Mg2+ relieves the MgATP2- and Mg-citrate inhibition under conditions where free ATP4-is negligible. We can assume that uncomplexed Mg2+ acts as positive effector by direct binding to the enzyme. These results emphasize the role of Mg2+ in the regulation of PFK activity in the erythrocyte.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D002951:Citrates / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D010732:Phosphofructokinase-1 / Q000097:blood*; D011485:Protein Binding
D002951:Citrates; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1; D008274:Magnesium