Photoreceptor rhodopsin:: structural and conformational study of its chromophore 11-cis retinal in oriented membranes by deuterium solid state NMR

Rhodopsin is the retinal photoreceptor responsible for visual signal transduction. To determine the orientation and conformation of retinal within the binding pocket of this membrane bound receptor, an ab initio solid state H-2 NMR approach was used. Bovine rhodopsin containing Il-cis retinal, specifically deuterated at its methyl groups at the C-19 or C-20 position, was uniaxially oriented in DMPC bilayers. Integrity of the membranes and quality of alignment were monitored by P-31 NMR. Analysis of the obtained H-2 NMR spectra provided angles for the individual labelled chemical bond vectors leading to an overall picture for the three dimensional structure of the polyene chain of the chromophore in the protein binding pocket around the Schiff base attachment site. (C) 1998 Federation of European Biochemical Societies.