title: Raman spectroscopy of selectively deuterated dimyristoylphosphatidylcholine: studies on dimyristoylphosphatidylcholine-cholesterol bilayers.
abstract: Dimyristoylphosphatidylcholine (DMPC), selectively deuterated in the sn-2 chain at the 3, 6, and 10 positions is used to probe DMPC-cholesterol interactions in multilamellar dispersions. Using the Raman spectral linewidths of the 2100 cm-1 C2H2 stretching modes as an index of membrane disorder, we demonstrate that cholesterol tends to order, or increase the number of trans carbon-carbon bonds within the DMPC acyl chain near the headgroup region at all temperatures. At low temperatures, cholesterol disorders the acyl chains near the methyl termini by inducing gauche conformers; cholesterol orders the entire chain at higher temperatures. These determinations are qualitatively consistent with conclusions drawn from deuterium nuclear magnetic resonance studies, but specifically reflect acyl chain trans/gauche isomerization on the 10(-12)-10(-13) s vibrational time scale.
mesh_terms: D002784:Cholesterol; D003903:Deuterium; D004134:Dimyristoylphosphatidylcholine; D008051:Lipid Bilayers; D013059:Spectrum Analysis, Raman; D013696:Temperature
chemical_list: D008051:Lipid Bilayers; D002784:Cholesterol; D003903:Deuterium; D004134:Dimyristoylphosphatidylcholine