Location of O-acetyl groups in S-657 using the reductive-cleavage method

A two-step procedure is described in this paper to identify the position of O-acetyl groups in S-657 polysaccharide. Reductive-cleavage experiments pe rformed on the fully methylated (base-catalyzed) polysaccharide, followed b y acetylation of anhydroalditols, identified individual sugar residues and their position of linkage. In a second experiment, the polysaccharide was m ethylated under neutral conditions leaving native acetate groups intact. Re ductive cleavage of the neutral methylated polysaccharide using CF3SO3SiMe3 as a catalyst, followed by acetylation in situ, identified sugar residues containing native acetate groups and established their position of substitu tion. Using this two-step procedure of analysis, S-657 polysaccharide is sh own to contain O-acetyl groups on the 2-position and the 2,6-positions of 3 -linked glucopyranosyl residues. (C) 2001 Elsevier Science Ltd. All rights reserved.