A β-(1 → 3)-arabinopyranosyltransferase that transfers a single arabinopyranose onto arabino-oligosaccharides in mung bean ( Vigna radiate) hypocotyls

Abstract

Arabinopyranosyltransferase (Ara pT) activity that results in the transfer of a single arabinopyranose (Ara p) residue from UDP-β- l-arabinopyranose (UDP-Ara p) to exogenous (1 → 5)-linked α- l-arabino-oligosaccharides labeled with 2-aminobenzamide (2-AB) at their reducing ends was identified in a particulate preparation obtained from 3-day-old mung bean ( Vigna radiate L. Wilezek) hypocotyls. The transferred Ara residue was shown to be β-(1 → 3)-linked to O-3 of the non-reducing terminal Ara f residues of the oligosaccharide using nuclear magnetic resonance spectroscopy together with glycosyl composition and glycosyl linkage composition analyses. The 2AB-labeled arabino-octasaccharide was the most effective acceptor substrate analyzed, although arabino-oligosaccharides with a degree of polymerization between 4 and 7 were also acceptor substrates. Maximum Ara pT activity was obtained at pH 6.5–7.0, and 20 °C in the presence of 25 mM Mn 2+ and 0.5% Triton X-100.