Structural studies of the O-antigen from vibrio cholerae O:2

The structure of the O-antigen from Vibrio cholerae O:2 has been investigated, mainly by methylation analysis, specific degradations, and n.m.r. spectroscopy, and concluded to involve the trisaccharide repeating-unit in which QuiNAc is 2-acetamido-2,6-dideoxyglucose and Sug is tentatively assigned as 5-acetamidino-7-acetamido-3,5,7,9-tetradeoxy- -glycero-β- -manno-nonulosonic acid. The acetamidino group is basic and, consequently, the polysaccharide is neutral. When this group is transformed into an N-acetyl group, by treatment with aqueous triethylamine, the polysaccharide becomes acidic.