Formation of a Nonreducing Trisaccharide, Selaginose, from Trehalose by a Cell-free System of Thermoanaerobium brockii.

Abstract

A nonreducing trisaccharide was formed in a reaction mixture containing trehalose and the cell-free extract of a thermophilic anaerobe, Thermoanaerobium brockii ATCC 35047. This saccharide was isolated from the mixture by trehalase digestion, alkaline treatment and preparative HPLC. From the results of partial acid hydrolysis, methylation analysis, and 13C-NMR analysis, the chemical structure of the saccharide was determined to be 2-O-α-D-glucopyranosyl α-D-glucopyranosyl α-D-glucopyrano- side (selaginose). Two enzymes related to Selaginose synthesis were partially purified by DEAEToyopearl column chromatography from the cell-free extract of T brockii. One was a trehalose phosphorylase (EC 2.4.1.64), which catalyzes the reversible phosphorolysis of trehalose into β-glucose-1-phosphate and glucose. The other synthesized kojibiose from β-glucose 1-phosphate and glucose. The latter enzyme was considered to be a novel phosphorylase. The hypothetical mechanism of selaginose synthesis was proposed as follows: trehalose+Pi→glucose+β-glucose 1-phosphate, β-glucose 1-phosphate +trehalose→selaginose+Pi.