β-furfuryl-β-glucoside: An endogenous activator of higher plant UDP-glucose: (1 → 3)-β-glucan synthase

Abstract

We have recently established the existence of endogenous activators of higher plant UDP-glucose: (1 → 3)-β-glucan synthase (Callaghan, T., Ross, P., Weinberger-Ohana, P., and Benziman, M. (1988) Plant Physiol. 86, 1099-1103). Here we report the purification and chemical analysis of the most abundant and specific compound, termed Activator I, isolated from Vigna radiata. This compound was extensively purified by a multistep procedure which yielded 0.1 mg of purified activator/g of fresh tissue. Enzyme digestion, neutral sugar analysis, GC/MS of permethylated derivatives, and NMR analysis of native Activator I indicated that the compound contains a single β-linked glucosyl residue. High resolution FAB-MS indicated an elemental composition of C11H16O7 (Mr = 260), with a calculated Mr of 98 for the aglycone. 13C, DEPT, and COSY NMR spectra showed that the aglycone molecule is an oxygen heterocycle of 5 carbons, consistent with a structure of β-furfuryl alcohol. Comparison of IR and GC/EI-MS spectra of authentic β-furfuryl alcohol with native aglycone confirmed the conclusion that Activator I is β-furfuryl-β-glucoside. Chemically synthesized β-furfuryl-β-glucoside has identical chemical properties and biological activity when compared with the purified endogenous activator (Ka = 50 μM).