External pH affects the acidification induced by ethanol. The apparent specific rate of acidification depends on the dissociation properties and production of carbon dioxide, acetic and lactic acid which are intermediates of ethanol oxidation. The organic acids are transported by Nernst-Einstein diffusion. We designed and identified a new and simple mathematical model that allows us to describe the effect of external pH on nonstationary transport of dissociated intermediates of ethanol oxidation.

• MeSH
• Acetates metabolism   MeSH
• Biological Transport, Active MeSH
• Models, Biological MeSH
• Candida metabolism   MeSH
• Potassium metabolism   MeSH
• Ethanol metabolism   MeSH
• Kinetics MeSH
• Hydrogen-Ion Concentration MeSH
• Lactic Acid MeSH
• Acetic Acid MeSH
• Lactates metabolism   MeSH
• Carbon Dioxide metabolism   MeSH
• Oxidation-Reduction MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetates MeSH
• Potassium MeSH
• Ethanol MeSH
• Lactic Acid MeSH
• Acetic Acid MeSH
• Lactates MeSH
• Carbon Dioxide MeSH

Protoplasts of Saccharomyces cerevisiae prepared by snail-gut juice treatment were compared in their transport properties with intact cells. 1. Constitutive monosaccharide transport (D-xylose, 6-deoxy-D-glucose), as well as inducible transport of D-galactose, were unaltered. 2. Phosphorylation-associated transport of 2-deoxy-D-glucose was enhanced in protoplasts, possibly as a consequence of removal of the unstirred layer of the cell wall. 3. Proton-driven transports of trehalose, L-leucine, L-proline and monophosphate could not be activated by preincubation with D-glucose, apparently owing to lack of proton-solute coupling in transport. Utilization of glucose was not depressed but respiration was reduced by about 50% while acidification of the external medium after glucose addition was inhibited by more than 90%. This may be related to the inability of protoplast plasma membrane H-ATPase to be activated by glucose and hence to impaired proton-translocating capacity. Uranyl ions inhibited generally much less in protoplasts than in intact cells although their binding to protoplasts was greater (maximum 0.68 fmol per cell but 3.2 fmol per protoplast).

• MeSH
• Biological Transport MeSH
• Ethanol metabolism   MeSH
• Glucose metabolism   MeSH
• Monosaccharides metabolism   MeSH
• Monosaccharide Transport Proteins MeSH
• Proton-Translocating ATPases metabolism   MeSH
• Protoplasts metabolism   MeSH
• Saccharomyces cerevisiae metabolism   MeSH
• Carrier Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ethanol MeSH
• Glucose MeSH
• Monosaccharides MeSH
• Monosaccharide Transport Proteins MeSH
• Proton-Translocating ATPases MeSH
• Carrier Proteins MeSH