?-Glucan synthetase activity in Golgi vesicles ofPetunia hybrida

Abstract
β-Glucan synthetase activity has been demonstrated in a Golgi vesicle fraction isolated from pollen tubes ofPetunia hybrida. Thisβ-glucan synthetase activity differs from that of most other higher plants in its inability to incorporate [14C]glucose from GDP-[14C]glucose. UDP-[14C]glucose, however, is an appropriate glucose donor for this enzyme. The optimum conditions for thisβ-glucan synthetase activity are: 1 mg Golgi vesicle protein/ml reaction mixture; pH=±8 and a temperature of 25°C. The newly synthesized alkali-insoluble glucan containsβ-1,3- as well as β-1,4-glucosidic linkages.