In the facultatively anaerobic yeast Saccharomyces cerevisiae the uptake rate and the accumulation ratio of 2-aminoisobutyric acid was decreased by some 30% by Fenton's reagent (FR), a powerful source of OH. radicals. Likewise, the uptake of glutamic acid, leucine and arginine was diminished. The mediated diffusion of 6-deoxy-D-glucose was not affected. The H+ symport of maltose and trehalose was inhibited by some 40% both in the initial rate and in the accumulation ratio. FR had a dramatic inhibitory effect when present during preincubation with 50 mmol/L glucose. In the obligately aerobic Lodderomyces elongisporus the uptake of all amino acids tested was decreased by 15-30%, that of 6-deoxy-D-glucose by about 10%. The initial rates of uptake of maltose and trehalose were depressed by FR by 40% and the acceleration of uptake observed after 8 min of incubation, was abolished by FR completely. Acidification rate of the external medium by S. cerevisiae in the presence of glucose or galactose was enhanced three-fold, that after subsequently added K+ was substantially decreased. FR appears to have a dual effect on sugar and amino acid transport processes in yeast: (1) it blocks carrier protein synthesis; (2) it inhibits the source of energy for transport. It does not appreciably affect the carrier proteins themselves.

• MeSH
• Biological Transport, Active drug effects   MeSH
• Amino Acids metabolism   MeSH
• Fungal Proteins metabolism   MeSH
• Kinetics MeSH
• Hydrogen-Ion Concentration MeSH
• Carbohydrate Metabolism MeSH
• Hydrogen Peroxide pharmacology   MeSH
• Saccharomyces cerevisiae drug effects   metabolism   MeSH
• Saccharomycetales drug effects   metabolism   MeSH
• Carrier Proteins metabolism   MeSH
• Iron pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Amino Acids MeSH
• Fenton's reagent MeSH Browser
• Fungal Proteins MeSH
• Hydrogen Peroxide MeSH
• Carrier Proteins MeSH
• Iron MeSH

Classical isolation procedure for plasma membrane H(+)-ATPase of Saccharomyces cerevisiae based on fractional centrifugation yielded always a roughly two-fold greater amount of membranes when starting from glucitol-preincubated than from glucose-preincubated yeast. This difference persisted all the way to the purified plasma membranes and to the purified H(+)-ATPase. The ATP-hydrolyzing activity by plasma membranes was roughly twice greater in glucose-preincubated cells than in the D-glucitol-preincubated ones while the purified enzyme was 7 times more active after glucose than after glucitol. Effects of diethylstilbestrol, suloctidil, erythrosin B, vanadate and dicarbanonaboranuide were very similar on plasma membrane-localized and purified ATPases of both forms, suggesting that both preparations contain the two ATPase forms, the glucose-preincubated one being richer in the activated form while the glucitol-preincubated one contains less of it.

• MeSH
• Adenosine Triphosphate metabolism   MeSH
• Cell Membrane enzymology   MeSH
• Enzyme Inhibitors pharmacology   MeSH
• Culture Media MeSH
• Proton-Translocating ATPases antagonists & inhibitors   isolation & purification   metabolism   MeSH
• Saccharomyces cerevisiae enzymology   growth & development   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Adenosine Triphosphate MeSH
• Enzyme Inhibitors MeSH
• Culture Media MeSH
• Proton-Translocating ATPases MeSH

Titratable acidity of the extracellular medium was compared with that calculated from pH changes in a suspension of Saccharomyces cerevisiae. After addition of cells to normal water the ratio of titratable acidity to the computed one was about 25, after addition of 50 mmol/L D-glucose it was about 13, after subsequent addition of K+ ions it was only 2. In heavy water the respective values were 30, 9, and 1. Apparently, the principal buffer-generating processes have to do with glucose metabolism but little with the K+/H+ exchange observed after addition of K+. D2O appears to block processes producing the buffering capacity of the medium, among them possibly extrusion of organic acids.

• MeSH
• Potassium Chloride pharmacology   MeSH
• Hydrogen-Ion Concentration MeSH
• Acids metabolism   MeSH
• Deuterium Oxide pharmacology   MeSH
• Buffers MeSH
• Saccharomyces cerevisiae drug effects   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Potassium Chloride MeSH
• Acids MeSH
• Deuterium Oxide MeSH
• Buffers MeSH