Interaction of Concanavalin A with External Mannan-Proteins of Saccharomyces cerevisiae. Glycoprotein Nature of beta-Glucanases

Abstract

β-Glucanases secreted into culture fluid by protoplasts or intact cells of the yeast Saccharomyrces cerevisiae were investigated for the presence of covalently linked carbohydrates. Gel filtration of the enzymes on Biogel A-1.5m showed that endo-β-1, 3-glucanase is a polydisperse enzyme of highmolecular weight which elutes in about the same volume as external yeast invertase. Exo-β-glucanase was eluted from the gel as a much lighter enzyme. Endo-β-1, 3-glucanase added to a mixture of extracellular mannoproteins was precipitated by concanavalin A to a similar extent to mannan, invertase and, acid phosphatase. Under the same conditions exo-β-glucanase did not interact with the lectin, but was partially precipitated from the solution in the absence of foreign mannan or mannan-proteins. The results show that endo-β-1, 3-glucanase of S. cerevisiae is a mannoprotein of a similar nature to external invertase and acid phosphatase. However, exo-β-glucanase appears to be a glycoprotein which does not contain the highly branched mannan polymer in its molecule.