[Structure and various characteristics of yeast beta-D-glucans]

Yeast cell wall contains mainly polysaccharides. Among them beta-1,3-D-glucans play role of the skeletal carcass of the yeast cell wall, while D-mannans represent its surface antigens. Mannans are built of alpha-1,6-linked polymannosyl backbone with the side chains consisting of alpha-1,2- and alpha-1,3-linked mannosyl units. The branching degree and length of the side chains are specific for individual yeast strains. By means of subsequent alkaline and acid extractions mannans and soluble glucans can be separated, leaving insoluble particulate glucan. The latter is inhomogenous and consists of microfibrillar and amorphous components. By means of gamma-irradiation these two components were separated and the structure of each was determined. It was found that microfibrillar glucan had a structure close to that of immunomodulating glucans isolated from Japanese fungi. By means of carboxymethylation of particulate glucan its water-soluble derivatives were prepared. Some immunopharmacological properties of the particulate glucan and its soluble derivatives are discussed in relation to their structural and physico-chemical characteristics.