The O‐Specific Polysaccharide Chain of Campylobacter Fetus Serotype A Lipopolysaccharide is a Partially O‐Acetylated 1,3‐Linked α‐D‐Mannan

A polysaccharide fraction liberated from Cumpylobacter fetus subsp. fetus serotype A lipopolysaccharide by mild acid hydrolysis followed by gel‐permeation chromatography contained a partially O‐acetylated D‐mannan chain, as an O‐specific polysaccharide, with a core oligosaccharide attached. The structure of the polysaccharide was studied by O‐deacetylation, methylation, and 1H‐ and 13C‐NMR spectros‐copy, including computer‐assisted analysis of the 13C‐NMR spectrum. A structure of→3)‐α‐D‐Manp2Ac‐(1→ was established as the structure of the 0‐specific polysaccharide, the degree of O‐acetylation of the mannose residues at position 2 being estimated as 80–907%. As judged by the ratio of mannose to core constituents, the D‐mannan chain consists on average of 10–12 monosaccharide units.