PHOTOLABILE, SPACER-MODIFIED OLIGOSACCHARIDES FOR PROBING MALTO-OLIGOSACCHARIDE BINDING-SITES IN PROTEINS

O-Deacylation and S-deacylation of the diastereomers of 2-azido-4-S-benzoyl-4-mercaptobutyl 2,3,4,6-tetra-O-acetyl-α-d-glucopyranoside (9) with methanolic sodium methoxide and coupling of the resulting thiol to methyl 3,4-anhydro-6-deoxy-β-l-arabino-hex-5-enopyranoside (2) gave the corresponding diastereomers of the spacer-modified disaccharide methyl 4-S-(3-azido-4-α-d-glucopyranosyloxybutyl)-6-deoxy-4-thio-α-d-xylo-hex-5-enopyranoside (10). Glucosylation of the diastereomers of 10 with α-cyclodextrin-CGTase and treatment of the products with beta-amylase gave the diastereomers of the spacer-modified oligosaccharides methyl 4-S-(3-azido-4-α-maltosyloxybutyl)-6-deoxy-4-thio-α-d-xylo-hex-5-eno pyranosides (11) and 4-S-(3-azido-4-α-maltotriosyloxybutyl)-6-deoxy-4-thio-α-d-xylo-hex-5-enopyranosides (12). The diastereomers of 10 each had a good affinity for pancreatic alpha-amylase and the maltose-binding protein from E. coli. The affinities of the diastereomers of 11 and 12 were higher by at least one order of magnitude. © 1990.