Kinetic evidence for a 'mnemonical' mechanism for rat liver glucokinase.
Inhibition studies of glucokinase were carried out with the products of the reaction, glucose 6-phosphate and MgADP-, as well as with ADP3-, Mg2+ and ATP4-. The results of these, together with those of kinetic studies of the uninhibited reaction described previously [Storer & Cornish-Bowden (1976) Biochem. J. 159, 7-14], indicate that the enzyme obeys a 'mnemonical' mechanism. This implies that the co-operativity observed with glucose as substrate arises because glucose binds differentially to two forms of the free enzyme that are not in equilibrium under steady-state conditions. The mechanism predicts the decrease in glucose co-operativity observed at low concentrations of MgATP2-. The product-inhibition results suggest that glucose 6-phosphate is released first and that it is possibly displaced by MgATP2- in a concerted reaction.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D005941:Glucokinase / Q000037:antagonists & inhibitors; D005958:Glucosephosphates / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008954:Models, Biological; D051381:Rats
D005958:Glucosephosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005941:Glucokinase; D008274:Magnesium