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Title: Effect of ethanol on fluxes of water and protons across the plasma membrane of Saccharomyces cerevisiae
Authors: Madeira, Ana
Leitão, Luís
Soveral, Graça
Dias, Patrícia
Prista, Catarina
Moura, Teresa
Loureiro-Dias, Maria C.
Keywords: Water fluxes
Proton fluxes
Saccharomyces cerevisiae
Issue Date: 2010
Publisher: Blackwell Publishing Ltd
Citation: FEMS Yeast Research. May 2010; 10 (3): 252–258
Abstract: Plasma membrane integrity, ability to transport substrates and maintenance of homeostasis represent obligatory requirements for efficient ethanol production by Saccharomyces cerevisiae. The effect of ethanol on water diffusion through the bilayer and on mediated water movements was evaluated by stopped flow spectro- scopy. Ethanol stimulated water diffusion and inhibited mediated water transport. In a strain overexpressing AQY1, the activation energy for water transport increased progressively (from 5.9 to 12.7 kcal mol􏰁1) for increasing ethanol concentrations (up to 12%v/v), indicating that mediated water transport lost importance as compared with water diffusion through the bilayer. The effect of ethanol on proton movements (inward by passive diffusion and outward through the PMA1 H1-ATPase) was evaluated by measuring the rate of extracellular alcalinization and acidification of unbuffered cell suspensions at different tem- peratures. Above 10% ethanol, H1 diffusion was strongly increased at 30 1C, but no effect was observed at 20 1C up to 12%, indicating the existence of a threshold above which ethanol has a marked effect. On H1 extrusion, ethanol had no effect at 20 1C, but induced a monotonous decrease at higher temperatures. Our results support the view that above a threshold of ethanol concentration, the membrane structure is disrupted, becoming very leaky to H1.
Description: The definitive version is available at A versão definitiva está disponível em
Peer review: yes
ISSN: 1567-1356
Publisher Version:
Appears in Collections:FF-DBBH - Artigos em Revistas Internacionais

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