Structure of the capsular antigen of Neisseria meningitidis serogroup K

The capsular antigen isolated from the culture liquid of a Neisseria meningitidis serogroup K(1811) fermentation consists of the 2-acetamido-2-deoxymannuronic acid disaccharide repeating unit as follows: ----3)-beta-D-ManpNAcA-(1----4)-beta-D-ManpNAcA-(1---- The polysaccharide is O-acetylated at the non-glycosylated C-4. Structural evidence has been obtained from sugar analysis, methylation analysis, as well as 1H and 13C NMR spectroscopy.