Premium
Chemical Characterization of Capsular Polysaccharide from Cryptococcus neoformans Serotype A‐D
Author(s) -
Ikeda Reiko,
Nishikawa Akemi,
Shinoda Takako,
Fukazawa Yoshimura
Publication year - 1985
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1985.tb02962.x
Subject(s) - polysaccharide , cryptococcus neoformans , mannose , serotype , glucuronic acid , xylose , biology , microbiology and biotechnology , ethanol precipitation , mannan , biochemistry , monosaccharide , acid hydrolysis , hydrolysis , chromatography , chemistry , fermentation
During a study of serotyping of Cryptococcus neoformans , we found that the type strain of C. neoformans (CBS 132) was serotype A‐D. This strain agglutinated with both factor 7 serum (specific for serotype A) and factor 8 serum (specific for serotype D) in our serotyping system. Therefore, we investigated the chemical structure of the antigenic capsular polysaccharide of this strain. The soluble capsular polysaccharide was obtained from the culture supernatant fluid by precipitation with ethanol. Column chromatography of the polysaccharide on DEAE‐cellulose yielded three fractions (F‐1 to F‐3). The major antigenic activity was found in the F‐3 fraction. The results obtained by methylation analysis, controlled Smith degradation‐methylation analysis, partial acid hydrolysis, and other structural studies of F‐3 polysaccharide indicated that the polysaccharide contains mannose, xylose, and glucuronic acid at a ratio of 7:2:2, and has a backbone of α(1–3)‐linked D ‐mannopyranoside residues with a single branch of β(1–2)‐xylose and glucuronic acid. The ratio of mannose residues with or without a branch in the F‐3 polysaccharide was 4:3 and its molecular weight calculated from the average of the degree of polymerization was 46,500 daltons. These results indicate that the chemical structure of the capsular polysaccharide of serotype A‐D is very similar to those from serotypes A and D, suggesting that small differences in the molar ratio and pattern of linkage of monosaccharides in the branch of the polysaccharides of the three serotypes may be responsible for their different specificities.