title: [Determination of intracellular pH by the distribution of benzoic acid in S. cerevisiae. Amino acid transport and proton gradient].
abstract: The internal pH (pHi) of Saccharomyces cerevisiae, wild type strain and its mutant rho- has been measured by the intra-extracellular distribution of 14C-benzoic acid. The values of pHi (external pH 4.5) change with the yeast strain and depend on the cellular metabolic conditions. The values of pHi and proton gradient in the wild type yeast are higher in energized than in starved cells: in energized cells pHi, 6.15 to 6.40, delta pH 1.65 to 1.90 or -97 to -112 mV; starved cells pH 5.90, delta pH 1.40 or -82 mV. In the rho- mutant, the values are lower than in the wild type yeast, in the same metabolic conditions. Energized rho- mutant cells, pH 6.05, delta pH 1.55 or -91 mV; starved cells, pHi 5.70, delta pH 1.20 or -71 mV. The proton conductors, DNP and PCP produce a decrease in pHi and delta pH and inhibition of L-leucine entrance by system S1, high affinity and low velocity and system S2, low affinity and high velocity. The obtained values of delta pH decrease and L-leucine transport inhibition, demonstrate that there is no strict relationship between the proton gradient across the cell membrane and the process of transport of L-leucine in yeast.
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
authors.forename: L C
authors.initials: LC
authors.lastname: de Bongioanni
authors.forename: E H
authors.initials: EH
authors.lastname: Ramos
mesh_terms: D019297:2,4-Dinitrophenol; D001565:Benzoates / Q000032:analysis*; D019817:Benzoic Acid; D001693:Biological Transport, Active / Q000187:drug effects; D001826:Body Fluids / Q000032:analysis*; D004140:Dinitrophenols / Q000494:pharmacology; D004563:Electrochemistry; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000032:analysis*; D007930:Leucine / Q000378:metabolism*; D010416:Pentachlorophenol / Q000494:pharmacology; D011522:Protons; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014867:Water / Q000032:analysis
chemical_list: D001565:Benzoates; D004140:Dinitrophenols; D011522:Protons; D014867:Water; D019817:Benzoic Acid; D010416:Pentachlorophenol; D007930:Leucine; D019297:2,4-Dinitrophenol
vernacular_title: Determinación del pH intracelular por distribución de ácido benzoico en S. cerevisiae. Transporte de aminoácidos y gradiente de protones.