Studies on the Antigenic Activity of Yeasts

I. Analysis of the Determinant Groups of the Mannan of Saccharomyces cerevisiae

Abstract

In order to determine the determinant antigenic group of the mannan of Saccharomyces cerevisiae, a series of inhibition tests were carried out employing oligosaccharides which separated from the acetolyzate and the hydrolyzate of the mannan. Tetraose, Manα1→3 Manα1→2 Manα1→2 Man², corresponding to the structure of the longer branching moieties of the mannan showed the strongest inhibition, while the isomer, Manα1→6 Manα1→6 Man, corresponding to the core moiety, produced only one-tenth the inhibition of the former. This provides evidence that the branching moieties of the mannan play important role in combining with antibody. The fact that the disaccharide, Manα1→3, showed significantly stronger inhibition than those of the other disaccharides, Manα1→2 Man and Manα1→6 Man, indicates that the most important part of the determinant group of the mannan isα1→3 linked D-mannose residue. The antigenic inactivity of the periodate-oxidized mannan containing unoxidized mannose residues indicates that the presence of 3-O-substituted-D-mannose residues adjacent to the n-mannose residues and joined with α1→2 linkages, are essential to fit the combining site of the antibody.