The influence of chain size and molecular weight on the kinetic constants for the span glucose to polysaccharide for rabbit muscle glycogen synthase.

The kinetic constants for the series of glucosyl acceptors for homogeneous rabbit muscle glycogen synthase I form free of glycogen were examined. The acceptors included glucose, maltose, G3, G4, G6, two hydrolyzed amyloses, amylodextrin and seven polysaccharides including amylopectin and glycogen. S0.5 and relative Vmax were estimated in each case. From these data a two site model of the enzyme is proposed, composed of a polysaccharide binding site and a separate catalytic site, the latter composed of several subsites.