Effect of dimethyl sulfoxide on phosphoryl transfer catalyzed by yeast hexokinase.

Hexokinase is a phosphotransferase that catalyzes phosphoryl transfer from ATP to glucose much more rapidly than the transfer from ATP to water (i.e., hydrolysis). Dimethyl sulfoxide has opposite effects on these two phosphotransferase activities: it enhances ATP hydrolysis and inhibits glucose phosphorylation. Xylose, a sugar that is non-phosphorylatable by hexokinase, enhances ATPase activity which is additive to activation by dimethyl sulfoxide, indicating that the mechanism of activation by dimethyl sulfoxide is different from that of xylose. These results suggest that it is possible to change the specificity of the enzyme in the presence of dimethyl sulfoxide.