Structural Features Inhibiting the Cross-Reaction of the Acidic Polysaccharide from Tremella mesenterica with a Type II Anti-pneumococcal Serum

Abstract

The immunochemical behaviors of native, deacetylated, and periodate-oxidized acidic polysaccharides of Cryptococcus laurentii NRRL Y-1401 and Tremella mesenterica NRRL Y-6151 and Y-6158 were examined with type II anti-pneumococcal horse serum. Although the native and deacetylated polysaccharide of Cryptococcus cross-reacted, the equivalent Tremella polysaccharides did not. Smith degradations of the polysaccharides produced a reversal of this effect as the degraded polysaccharides of Tremella cross-reacted whereas that of Cryptococcus now failed to react. On the basis of this study it has now been established that the failure of the Tremella polysaccharides to cross-react with type II antiserum is due to steric interactions. The critical factor involved in the steric hindrance can be attributed to some strategically placed xylose units located in the vicinity of the glucuronic acid determinants. It has also been demonstrated that the periodate stability of the glucuronic acid residues of the Tremella polysaccharides is probably due to the presence of O-acetyl groups on the C-3 position of these residues.