Echinocandin inhibition of 1,3-beta-D-glucan synthase from Candida albicans

The cyclic peptide antibiotic echinocandin was found to inhibit 1,3-beta-D-glucan synthase activity present in a mixed membrane fraction from Candida albicans. Addition of antibiotic reduced the Vmax of the enzyme, but the Km was unaffected. GTP stimulated enzyme activity approximately 4-fold, but did not affect the percentage inhibition of the enzyme by echinocandin. Treatment of the reaction products with alpha-amylase and beta-glucanase confirmed that the polymer synthesised was 1,3-beta-D-glucan, not glycogen.