Probing acceptor specificity in the glycogen synthase reaction with polymer-bound oligosaccharides

Polymers having maltose and maltotriose side-chains were synthesized by attaching 4-carboxy-2-nitrobenzyl 4-O-alpha-D-glucopyranosyl-beta-D-glucopyranoside or 4-carboxy-2-nitrobenzyl O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-O-beta-D- glucopyranoside, respectively, to aminoethyl-substituted polyacrylamide gel beads. Subsequently, the two polymers, and analogous polymers having D-glucose and cellobiose side-chains, served in a comparative study as acceptors in the glycogen synthase (UDP-D-glucose: glycogen 4-alpha-glucosyltransferase, EC 2.4.1.11) reaction. Highest transfer (4.2%) was observed for the polymer bearing maltotriose groups. The bound saccharides were then removed by irradiation (greater than 320 nm), and examination of them demonstrated that alpha-D-glucosyl oligomerization in the glycogen synthase reaction had occurred.