A calorimetric investigation of the interaction of short chain alcohols with unilamellar DMPC liposomes

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The molecular mechanisms by which ethanol and other short-chain alcohols perturb biological systems have been suggested to involve specific interactions with proteins and/or nonspecific interactions with the lipid bilayer part of biological membranes. To gain insight into the influence of alcohols on well-defined lipid bilayers, isothermal titration calorimetry (ITC) is used to determine the excess partial molar enthalpy of alcohol in liposome suspensions as well as the excess partial molar enthalpy of liposomes in dilute alcohol-water mixtures at temperatures above the main phase transition of dimyristoyl phosphatidylcholine (DMPC). The alcohols investigated were ethanol, 1-propanol, and 1-butanol. The calorimetric data were used to evaluate molecular interactions and based on a simple partitioning model the standard molar enthalpy of transferring alcohol from water into unilamellar DMPC liposomes was determined. The results reveal that the interaction of short-chain alcohols with the DMPC lipid bilayer is endothermic and strongly dependent on temperature indicating that a major contribution to the energetics of the association is dehydration of nonpolar moieties. Furthermore the data show that the interactions become increasingly unfavorable in terms of enthalpy with increasing size of the nonpolar surface area of the alcohol.

Original languageEnglish
JournalJournal of Physical Chemistry B
Issue number22
Pages (from-to)4751-4756
Number of pages6
Publication statusPublished - 3 Jun 1999

ID: 236895097