Comparison of the mannan structure from the cell-wall mutant Candida sp. M-7002 and its wild type. II. Immunochemical properties of the mannans.

The structure of the proteomannans from the cell-wall mutant Candida sp. and its parent strain was further studied by immunochemical methods. Alkaline titration showed that the phosphate is present in the form of diester and mild acid treatment released mannose from both of the mannans. In the wild-type mannan, the phosphorylated side-chain oligosaccharides gave 85% inhibition and a mannopentaose side chain having alpha 1--3 linkage in the nonreducing terminal also gave 40% inhibition in the homologous precipitin reaction. This indicates that the immunodominant side chain of the Candida sp. wild type mannan is the phosphorylated mannopentaose which has an (alpha 1--3)-linked nonreducing terminal. In the mutant system, a significant reactivity in the cross reaction between the mutant antiserum and Kloeckera brevis mannan indicates that the immunodeterminant of the mutant mannan may be a structural analogue of the side-chain oligosaccharide from K. brevis, which has phosphorylated (alpha 1--3)-linked mannotriose. However, no definite results were obtained in the inhibition studies. On the basis of the results from chemical, enzymatical and immunological experiments, the side-chain structure and macromolecular models of Candida sp. wild-type and mutant mannans are proposed.