The effect of the osmotically active compound concentration difference on the passive water and proton fluxes across a lipid bilayer

Przybyło, Magdalena (author), Drabik, Dominik (author), Doskocz, Joanna (author), Iglič, Aleš (author), Langner, Marek (author)

The molecular details of the passive water flux across the hydrophobic membrane interior are still a matter of debate. One of the postulated mechanisms is the spontaneous, water-filled pore opening, which facilitates the hydrophilic connection between aqueous phases separated by the membrane. In the paper, we provide experimental evidence showing that the spontaneous lipid pore formation correlates with the membrane mechanics; hence, it depends on the composition of the lipid bilayer and the concentration of the osmotically active compound. Using liposomes as an experimental membrane model, osmotically induced water efflux was measured with the stopped-flow technique. Shapes of kinetic curves obtained at low osmotic pressure differences are interpreted in terms of two events: the lipid pore opening and water flow across the aqueous channel. The biological significance of the dependence of the lipid pore formation on the concentration difference of an osmotically active compound was illustrated by the demonstration that osmotically driven water flow can be accompanied by the dissipation of the pH gradient. The application of the Helfrich model to describe the probability of lipid pore opening was validated by demonstrating that the probability of pore opening correlates with the membrane bending rigidity. The correlation was determined by experimentally derived bending rigidity coefficients and probabilities of lipid pores opening.

• Language: English
• Keywords: lipid bilayer, water transport, proton transport, water activity, membrane mechanics
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering; MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 19 str.
• Numbering: Vol. 22, iss. 20, art. 11099
• PID: 20.500.12556/RUL-136231
• UDC: 577
• ISSN on article: 1422-0067
• DOI: 10.3390/ijms222011099
• COBISS.SI-ID: 81110275
• Publication date in RUL: 20.04.2022

Record is a part of a journal

• Title: International journal of molecular sciences
• Shortened title: Int. j. mol. sci.
• Publisher: MDPI
• ISSN: 1422-0067
• COBISS.SI-ID: 2779162

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 14.10.2021

Secondary language

• Language: Slovenian
• Keywords: lipidni dvosloj, transport vode, transport protona, vodna aktivnost, membranska mehanika