β Scribed by T.H. Fischer; G.C. Levy
No coin nor oath required. For personal study only.
The effect of rhodopsin incorporation on molecular motion in L-,a-dimyristoylphosphatidylcholine (DMPC) bilayers is analyzed with nitroxide ESR and proton NMR techniques. A partial, binary phase diagram for DMPC-rhodopsin is constructed by studying the partitioning of 2,2,6,6-tetramethylpiperidine-l-oxyl ITempo) between polar and hydrophobic domains as a function of temperature and system composition. Proton NMR spin-lattice relaxation measurements show that rhodopsin is associated with a domain of approx. 50 DMPC molecules which have reduced choline methyl mobilities. ESR studies, utilizing nitroxide-labeled fatty acid probes, indicate that rhodopsin immobilizes the outer half of the hydrophobic region in rhodopsin containing DMPC bilayers. Additional ESR studies, involving a nitroxide label placed in the middle of the membrane, as well as proton chain methyl spin4attice relaxation measurements, indicate only slight rhodopsin-induced immobilization in the central part of the membrane.
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