Preparation and analysis of yeast cell wall mannoproteins, immune enchancing materials, from cell wall mutant Saccharomyces cerevisiae

Yeast cell wall matrix particles are composed entirely of mannoprotein and β-glucan. The mannoproteins of yeast cell wall can systemically enhance the immune system. We previously purified and analyzed alkali-soluble β-glucans [β-(1,3)- and β-(1,6)-glucans] [10]. In the present study, a wild-type strain was first mutagenized with ultraviolet light, and the cell wall mutants were then selected by treatment with 1.0 mg/ml laminarinase (endo-β-(1,3)-D-glucanase). Mannoproteins of Saccharomyces cerevisiae were released by laminarinase, purified by concanavalin-A affinity and ion-exchange chromatography. The results indicated that the mutants yielded 3-fold more mannoprotein than the wild-type. The mannoprotein mass of mutant K48L3 was 2.25 mg/100 mg of yeast cell dry mass. Carbohydrate analysis revealed that they contained mannose, glucose, and N-acetylglucosamine. Saccharomyces cerevisiae cell wall components, mannoproteins, are known to interact with macrophages through receptors, thereby inducing release of tumor necrosis factor alpha (TNF-α) and nitric oxide. Mannoprotein fractions in the present study had a higher macrophage activity of secretion of TNF-α and nitric oxide and direct phagocytosis than positive control (1 μg of lipopolysaccharide). In particular, F1 and F3 fractions in mannoproteins of K48L3 enhanced and upregulated the activity of nitric oxide secretion and macrophage phagocytosis by approximately two- and four-fold, respectively.