Yeast hexokinase binding studies

Other Mg +- and Mn +-activated enzymes in which the metal is thought not to act in a bridging role include yeast hexokinase, yeast enolase, and arginine kinase. The enhancement of p.r.r. by Mn + and Cu + has been used to study the interaction of these metal ions with ribonuclease A. The author concludes that, as their concentration is increased, the metal ions first activate the enzyme by binding to the phosphate groups on the substrate (RNA) and then inhibit by blocking the active sites on the enzyme. 

---