title: The interaction of n-alkanols with lipid bilayer membranes: a 2H-NMR study.
abstract: The interaction of eight n-alkanols with bilayers of dimyristoylphosphatidylcholine (DMPC) has been studied by deuterium nuclear magnetic resonance (2H-NMR). At comparable temperatures and concentrations of solute in the bilayer, order parameters measured at the 1-methylene segment of the n-alkanols show a maximum for n-dodecanol. For both n-dodecanol and n-tetradecanol, orientational ordering shows a maximum at the C-4 to C-7 methylene segments, with labels at both ends of the n-alkanol exhibiting reduced order. These observations are consistent with earlier findings for n-octanol and n-decanol. Unlike the longer chain n-alkanols, ordering in n-butanol decreases from the hydroxyl group end to the methyl group end of the molecule. Orientational ordering at nine inequivalent sites in DMPC, has also been measured as a function of temperature, for bilayers containing n-butanol, n-octanol, n-dodecanol and n-tetradecanol. At the 3R,S sites on the glycerol backbone, for comparable temperatures and solute concentrations, n-butanol produces a larger disordering than the other n-alkanols. This result probably reflects the greater fraction of time spent by the hydroxyl group of n-butanol in the vicinity of the lipid polar head group compared with the hydroxyl group in longer chain n-alkanols. It was found that n-octanol orders the acyl chains of DMPC, unlike n-butanol which disorders them, and the longer chain n-alkanols which have little effect. Within experimental error, the effect of n-dodecanol on order at all sites in DMPC is the same as n-tetradecanol. The influence of n-alkanols on DMPC ordering at twelve sites has been compared with that of cholesterol which is shown to interact with DMPC bilayers in a distinctly different manner from the n-alkanols.
authors.affiliation: Department of Biochemistry, Northeastern Ohio Universities College of Medicine, Rootstown 44272.
authors.forename: P W
authors.initials: PW
authors.lastname: Westerman
authors.forename: J M
authors.initials: JM
authors.lastname: Pope
authors.forename: N
authors.initials: N
authors.lastname: Phonphok
authors.forename: J W
authors.initials: JW
authors.lastname: Doane
authors.forename: D W
authors.initials: DW
authors.lastname: Dubro
mesh_terms: D000438:Alcohols; D004134:Dimyristoylphosphatidylcholine; D008051:Lipid Bilayers; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids; D008968:Molecular Conformation; D013696:Temperature
chemical_list: D000438:Alcohols; D008051:Lipid Bilayers; D008563:Membrane Lipids; D004134:Dimyristoylphosphatidylcholine