beta-Glucanases from Candida albicans: purification, characterization and the nature of their attachment to cell wall components

beta-Glucanase activities were found associated with Candida albicans and their culture fluids. Mild acid treatment of the organisms led to rapid inactivation of beta-glucanase activities, the degree of loss increasing with the age of the cultures; the results suggested an extracytoplasmic location of the cell-associated enzymes. Most of the beta-glucanase activities were associated with the cell walls in organisms phenotypically resistant to amphotericin B methyl ester (AME). Two proteins (I and II) exhibiting beta-glucanase activity were isolated and purified by conventional procedures from cell-free extracts, cell-wall autolysates and culture fluids of C. albicans sensitive and phenotypically resistant to AME. The purified enzymes appeared homogeneous on isoelectric focusing, gel electrophoresis and ultracentrifugation, with molecular weights of 150000 (I) and 49000 (II). Both enzymes hydrolysed cell walls purified from AME-sensitive and phenotypically resistant organisms, but showed different substrate specificities and patterns of activity. Enzyme II hydrolysed (1 leads to 3)-beta-glycans by an endolytic mechanism releasing laminaritetraose as the initial product. Glucose was the only product released by enzyme I. The prop...Continue Reading