The Klebsiella O3 lipopolysaccharide isolated from culture fluid: structure of the polysaccharide moiety.

In a series of our earlier studies, the O3 antigen isolated from culture supernatant of Klebsiella pneumoniae strain Kasuya (O3:K1) (KO3) was shown to exhibit very strong adjuvant activity in mice. KO3 obtained was homogeneous in analyses by either gel filtration or ultracentrifugation. Its molecular weight determined by ultracentrifugal analysis was greater than 2 X 10(6). It contained 37.9% C, 6.20% H, 0.24% N, and less than 0.1% P. KO3 was degraded into the polysaccharide moiety and lipid moiety (about 20%) by hydrolysis with 1% acetic acid at 100 C for 1 hr. The molecular weight of the polysaccharide moiety obtained by the hydrolysis was 16,200 as determined by the Somogyi-Nelson method. Chemical analyses using methylation analysis and Smith degradation as the principal methods indicated that the polysaccharide moiety consisted of a mannan which has a pentasaccharide repeating unit of alpha-mannosyl-1,3-alpha-mannosyl-1,2-alpha-mannosyl-1,2-alpha-mannosyl-1, 2-alpha-mannose joined through alpha-1,3-mannosyl linkages. The number of repetitions was less than 20. The fact that minor components such as 2-keto-3-deoxyoctonate and glucose were detected suggests the presence of a core oligosaccharide, but its precise structure is unknown.