title: PMR studies of phosphatidylcholine-cholesterol vesicles interacting with lucensomycin.
abstract: Spin-lattice relaxation times (T1) were measured above the phase transition temperature on sonicated vesicles of egg- or dipalmitoyl-phosphatidylcholine containing cholesterol and/or the polyenic antibiotic, lucensomycin. T1 values of only the terminal methyl groups of the fatty acyl chains were significantly reduced by cholesterol. Lucensomycin caused, more markedly in cholesterol-containing vesicles, a selective reduction of the T1 values of the N-methyl groups. An even more conspicuous decrease, occurring only in cholesterol-containing vesicles, was observed for the transverse relaxation times (T2) of the N-methyl signals upon addition of lucensomycin. The polyene failed to remove the well-known broadening effect of cholesterol on phosphatidylcholine methylene signals. These results indicate that as lucensomycin binds to cholesterol-containing membranes, there is a detectable perturbation of the dynamic structure of the N-methyl groups with an increase in the degree of motional anisotropy. But the non-polar region of the bilayer seems not significantly perturbed by the polyene.
mesh_terms: D000935:Antifungal Agents; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002621:Chemistry; D002784:Cholesterol; D008081:Liposomes; D008155:Lucensomycin; D009682:Magnetic Resonance Spectroscopy; D010713:Phosphatidylcholines; D011522:Protons; D013696:Temperature
chemical_list: D000935:Antifungal Agents; D008081:Liposomes; D010713:Phosphatidylcholines; D011522:Protons; D008155:Lucensomycin; D002784:Cholesterol