title: Appel-Lee synthesis of glycosyl inositols, substrates for inositol dehydrogenase from Bacillus subtilis.
abstract: We recently reported that inositol dehydrogenase (EC 1.1.1.18) from Bacillus subtilis can catalyze the highly stereoselective oxidation of 1l-4-O-substituted myo-inositol derivatives, as well as disaccharides melibiose and isomaltose, but not gentiobiose or maltose, consistent with the requirement of an alpha-(1-->6) linkage. We believed that the enzyme might therefore catalyze efficient stereoselective oxidation of the appropriate alpha-linked glycosyl inositols. We have synthesized alpha-D-glucopyranosyl-(1-->4)-(DL)-myo-inositol and alpha-d-galactopyranosyl-(1-->4)-(DL)-myo-inositol using the Appel-Lee protocol to couple benzyl-protected glycosyl donors to protected inositols. This method failed in our hands using glycosyl donors derived from D-mannose and 2-azido-2-deoxy-D-glucose. When myo-inositol 1,3,5-monoorthoformate is used as the acceptor, the reaction is regiospecific for the 4/6-position. We report here the mildest conditions known for the removal of the orthoformate group. 2-Azido-2-deoxy-alpha-D-glucopyranosyl-(1-->4)-(DL)-myo-inositol was synthesized using the trichloroacetimidate derivative as the donor, and all three pseudo-disaccharides were substrates for inositol dehydrogenase. The glucopyranosyl and galactopyranosyl derivatives displayed apparent second-order rate constants comparable to that of myo-inositol.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9.
authors.forename: Richard
authors.initials: R
authors.lastname: Daniellou
authors.forename: David R J
authors.initials: DR
authors.lastname: Palmer
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D002240:Carbohydrate Sequence; D006031:Glycosylation; D007294:Inositol / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D007064:L-Iditol 2-Dehydrogenase; D015394:Molecular Structure; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D009844:Oligosaccharides; D007294:Inositol; D010088:Oxidoreductases; D007064:L-Iditol 2-Dehydrogenase