Susceptibility of UDP-Glucose:(1,3)-β-Glucan Synthase to Inactivation by Phospholipases and Trypsin

Abstract
UDP-glucose:(1,3)-.beta.-glucan synthase from Beta vulgaris L. was rapidly inactivated by treatment with phospholipases C, D, and A2. Enzyme activity could not be restored to the phospholipase-treated enzyme by the addition of phosphatidylethanolamine or other phospholipids. Membrane-bound and solubilized glucan synthase were also trypsin-labile with inactivation rates equal in the presence or absence of divalent cations or chelators. Gradual activity declines were observed in membranes incubated with divalent cations, but not with chelators.