The biosynthesis of beta-(1,3) linked glucans and possibly cellulose in higher plants is catalyzed by the plasma membrane enzyme glucan synthase (UDP-glucose:(1,3)-beta-glucan synthase). To understand the biochemical basis for the regulation of cell wall polysaccharide biogenesis and wound healing, it is necessary to identify and characterize the polysaccharide synthases. Glucan synthase is ubiquitous in plant tissue but has proven to be a stubborn enzyme to purify to homogeneity by standard protein fractionation techniques. It is now possible to obtain stabilized and highly-enriched enzyme preparations from a range of plant sources using differential solubilization with the detergent CHAPS, gel filtration chromatography and product entrapment. This research will resolve the longstanding question of whether beta-(1,3) and beta-(1,4) linked glucans are biosynthesized by one enzyme or by several where each is distinct for the formation of one linkage type. Furthermore, unambiguous identification of the polypeptides which comprise the glucan synthase complex will facilitate identification and cloning of the gene or genes which code for important enzymes in plant cell wall biogenesis. Cellulose, an immensely abundant biopolymer, serves a structural role in plant cells. Its biosynthesis is only incompletely understood because of the difficulties in isolating the enzymes involved from cell walls. This project focuses on the major regulated enzyme and will provide important information on how cell walls are made and kept intact.
