Effect of inhibitors on acid production by baker's yeast.
Glucose-induced acid extrusion, respiration and anaerobic fermentation in baker's yeast was studied with the aid of sixteen inhibitors. Uranyl(2+) nitrate affected the acid extrusion more anaerobically than aerobically; the complexing of Mg2+ and Ca2+ by EDTA at the membrane had no effect. Inhibitors of glycolysis (iodoacetamide, N-ethylmaleimide, fluoride) suppressed acid production markedly, and so did the phosphorylation-blocking arsenate. Fluoroacetate, inhibiting the citric-acid cycle, had no effect. Inhibition by uncouplers depended on their pKa values: 2,4,6-trinitrophenol (pKa 0.4) less than 2,4-dinitrophenol (4.1) less than azide (4.7) less than 3-chlorophenylhydrazonomalononitrile (6.0). Inhibition by trinitrophenol was only slightly increased by its acetylation. Cyanide and nonpermeant oligomycin showed practically no effect; inhibition by dicyclohexylcarbodiimide was delayed but potent. The concentration profiles of inhibition of acid production differed from those of respiration and fermentation. Thus, though the acid production is a metabolically dependent process, it does not reflect the intensity of metabolism, except partly in the first half of glycolysis.
D000143:Acids / Q000378:metabolism*; D001149:Arsenates / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D007460:Iodoacetamide / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D009840:Oligomycins / Q000494:pharmacology; D010851:Picrates / Q000494:pharmacology; D011190:Potassium Cyanide / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D014301:Trinitrobenzenes / Q000494:pharmacology; D014502:Uranyl Nitrate / Q000494:pharmacology
D000143:Acids; D001149:Arsenates; D001386:Azides; D004140:Dinitrophenols; D009570:Nitriles; D009840:Oligomycins; D010851:Picrates; D014301:Trinitrobenzenes; D014502:Uranyl Nitrate; D000431:Ethanol; D004024:Dicyclohexylcarbodiimide; D012969:Sodium Fluoride; D004492:Edetic Acid; D011190:Potassium Cyanide; D005033:Ethylmaleimide; D007460:Iodoacetamide