Synthesis of (1→2)-β-D-Glucan by Cell-free Extracts of Agrobacterium radiobacter IFO 12665b1 and Rhizobium phaseoli AHU 1133

Abstract

Particulate preparations from Agrobacterium radiobacter IFO 12665b1 and Rhizobium phaseoli AHU 1133 have been shown to catalyze the synthesis of (1→2)-β-D-glucan from UDP-D- [¹⁴C]glucose. The (1→2)-β-D-glucans synthesized are suggested to be in a cyclic form without other glycosidic linkages and to consist of a mixture of several components with degrees of polymerization of 17 and more. The enzyme systems from A. radiobacter IFO 12665b1 and R. phaseoli AHU 1133 both required Mn²⁺ and had optimum activities at pH 7.5-8, and their Km values for UDPD-[¹⁴C]glucose were 5×10^-5M and 3.3×10^-5M, respectively.