Abstract
The O-specific polysaccharide moiety (018ac polysaccharides) of the 018ac antigen (lipopolysaccharide) from E. coli 2980 (018ac:k5:Fim+:H-) was isolated in pure form by degradation of the lipopolysaccharide and chromatography on Sephadex G-50. The primary structure of the 018ac polysaccharide was elucidated by composition, fragmentation procedures, methylation analysis and NMR spectrosocpy. The polysaccharide consists of repeating units of the pentasaccharide which are joined in the polymer by .alpha.-1,2-linkages.