Occurrence of an endo-1,3-β-glucanase in culture fluids of the yeast Candida utilis. Purification and characterization of the enzyme activity

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Abstract
The endo-1,3-.beta.-glucanase (EC 3.2.1.6) secreted into the culture medium by cells of C. utilis was isolated and purified to homogeneity on polyacrylamide-gel electrophoresis and in ultracentrifugation studies (s20,w = 1.97 S). The purified enzyme represented only 0.001% of the total 1,3-.beta.-glucanase activity, the remainder being due to an exo-1,3-.beta.-glucanase enzyme, and behaved as an acidic glycoprotein (pI [isoelectric point], 3.3) in isoelectric-focusing experiments. The MW was estimated to be 21,000 by gel filtration and polyacrylamide-gel electrophoresis. Studies on the hydrolysis of different substrates showed that the enzyme was only able to break down (1 .fwdarw. 3)-.beta.-linkages, by an endo-splitting mechanism. Glucono-.delta.-lactone, D-glucoronolactone and heavy metal ions such as Hg2+ were inhibitors of the enzyme activity. The function of this endo-.beta.-glucanase in C. utilis is discussed.