Measurement of rotational motion in membranes using fluorescence recovery after photobleaching.
A method has been developed for the measurement of the rotational motion of membrane components. In this method fluorescent molecules whose transition dipole moments lie in a given direction are preferentially destroyed with a short intense burst of polarized laser radiation. The fluorescence intensity, excited with a low intensity observation beam of polarized laser radiation, changes with time as the remaining fluorescent molecules rotate. The feasibility of the method has been demonstrated in a study of the rotation of the fluorescent lipid probe, dil ([bis,-2-(N-octadecyl-3,3-dimethyl-1-benzo[b]pyrrole]-trimethincyanine iodide) incorporated into membranes composed of distearoylphosphatidylcholine (DSPC) or dipalmitoylphosphatidylcholine (DPPC) and 0.20 mol% cholesterol, below the main chain-melting transition temperatures of the phosphatidylcholines. Rotation times in the 0.6-800 s range were observed. The fluorescence recovery (or decay) curves are in satisfactory agreement with theoretical calculations.
D002784:Cholesterol; D008051:Lipid Bilayers; D008081:Liposomes; D008433:Mathematics; D008566:Membranes / Q000648:ultrastructure*; D008954:Models, Biological; D008968:Molecular Conformation; D010713:Phosphatidylcholines; D010782:Photolysis; D013050:Spectrometry, Fluorescence / Q000379:methods
D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D002784:Cholesterol