Permeability alterations induced in yeast by high levels of the polyene antifungal antibiotic nystatin were examined. Glycolytic activity could be protected against nystatin either by adding ca 0.04 M K+ and NH4+ salts (stationary phase cells) or by 0.01 M K+ and NH4 salts and the cofactors essential for a cell-free glycolytic system (log phase cells or protoplasts). Under these conditions there was leakage of K+, NH4+, nucleotides and some protein, although glycolytic activity remained with the treated cells or protoplasts even after repeated washing. Pyruvate decarboxylase in NY-treated cells became accessible to pyruvate ions, but glucoses-phosphate and fructose-1,6-diphosphate were still not fermented. The rate of CO2 production by NY-treated cells or osmotically-lysed protoplasts did not exceed 25 to 30% of that obtained with the original preparations. The nature of the membrane alterations is discussed.
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Sutton et al. (1961) studied this question.