Thermodynamic interpretation of effects of alcohols on membrane lipid fluidity

✍ Scribed by R.A. Boigegrain; Y. Fernandez; M. Massol; S. Mitjavila

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 438 KB
• Volume: 35
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(84)90075-6

✦ Synopsis

The effect of a series of amphiphilic compounds, the first eight n-aliphatic alcohols, on the fluidity of rat enterocyte brush border was determined by ESR using 5-doxyl stearic acid as a lipid spin probe. Packing order variations are compared to the relative hydrophobic effect of the alcohols. The concentrations, [Ci] ~ of each alcohol that decrease the membrane 2T'II value by 5%, vary by a factor of 1500 from methanol to octanol. From [Ci] ~, the membrane concentrations C m and the variation of free energy AF ° due to the incorporation of the alcohols in the lipids, were calculated. These calculations were performed taking into account the respective volumes of the aqueous phase and the membrane lipids. C m is of the order of 0,18 mol/kg for the odd chain length alcohols and of 0.27 mol/kg for the even alcohols. The value of AF ° in cal/mol -CH2-is -687 cal on average for the eight alcohols. This work shows that for all the alcohols, the concentrations at equilibrium in the membrane and in the aqueous phase are respectively in agreement with Meyer and Overton's theory and with the gradient of free energy which constitutes the most general index of interaction of iipophilic substances with membranes.