title: Effects of very small amounts of cholesterol on gel-phase phosphatidylcholine membranes.
abstract: The mobility of 5-doxyl stearic acid spin label (5-SASL) in the gel phase of dipalmitoylphosphatidylcholine membranes between the main transition and subtransition temperatures was studied as a function of cholesterol content. Very small amounts of cholesterol (0.01-1 mol%) cause a dramatic increase in the mobility of 5-SASL. Temperature-drop experiments from 38 degrees C to 28 degrees C were made across the pretransition temperature and the rate of approach to equilibrium was measured. Cholesterol at low concentrations also affects this rate. The membrane reached equilibrium after 10 h in the absence of cholesterol, 3 h at 0.01 mol% cholesterol, and less than 10 min at 0.03 mol% cholesterol.
mesh_terms: D002784:Cholesterol / Q000494:pharmacology*; D003497:Cyclic N-Oxides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D008563:Membrane Lipids / Q000378:metabolism*; D010713:Phosphatidylcholines; D013113:Spin Labels / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
chemical_list: D003497:Cyclic N-Oxides; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D013113:Spin Labels; C005072:5-doxylstearic acid; D002784:Cholesterol