INHIBITION OF PHOSPHATE AND ARSENATE UPTAKE IN YEAST BY MONOIODOACETATE FLUORIDE 2,4-DINITROPHENOL AND ACETATE

1. Arsenate and phosphate uptake by the yeast Saccharomyces cerevisiae Delft II is inhibited completely by 3 mM monoiodoacetate, 20 mM fluoride, 0.1 mM 2,4-dinitrophenol and 60 mM acetate under anaerobic conditions at pH 4.5. 2. Monoiodoacetate, 2,4-dinitrophenol and acetate decrease not only the maximum rate of uptake but also the Km for this process. 3. The percent decrease in the rates of glycolysis and phosphate uptake caused by monoiodoacetate is about the same. The three other inhibitors inhibit glycolysis only at concentrations much higher than those which decrease phosphate uptake. 4. The cellular ATP concentration is strongly decreased by 3 mM monoiodoacetate and 20 mM fluoride (90%), but much less by 0.1 mM 2,4-dinitrophenol (60%) and by 60 mM acetate (25%). 5. Possible ways in which the inhibitors may affect Pi and Asi uptake are discussed. © 1969.