Partitioning of Small Alcohols into Dimyristoyl Phosphatidylcholine (DMPC) Membranes: Volumetric Properties

• DOI: 10.1021/jp001540l
• Publication Date: 2002-07-26T06:04:16Z
• Authors: Peter Westh; Christa Trandum
• Keywords: Partial specific volume; Hexanol; Benzyl alcohol; Fatty alcohol

Volume changes associated with the partitioning of eight different alcohols and acetone into unilamellar vesicles dimyristoyl phosphatidylcholine in fluid state was investigated by newly designed, automated titration densitometric equipment. The change free volume process, expressed specific excess solutions, positive for all solutes. magnitude total per mole alcohol partitioned, ΔVm, calculated combining volumetric data previously published coefficients. For aliphatic 1-alcohols, ΔVm increased gradually from 3 cm3/mol ethanol to ∼29 1-hexanol. Values cyclic c-hexanol benzyl were ∼3 times smaller than compounds a similar molecular weight. composition dependence functions could be determined sufficient accuracy allow estimation partial three components (water, alcohol, lipid). These elucidate contribution each component measured expansion system. increased, whereas water diminished as result process. This suggests that increase membrane−alcohol complex is larger whole system (ΔVm) because latter partially compensated contraction solvent. results support picture which adsorption promotes loosening packing an content lipid bilayer membranes.