title: Interpretation of the resonance Raman spectrum of bathorhodopsin based on visual pigment analogues.
abstract: Resonance Raman spectra of visual pigment analogues have been used to evaluate various models for the structure of the retinal chromophore in bathorhodopsin. Deuteration or removal of the 18-methyl on the beta-ionyl ring or of the 19-methyl on the polyene chain demonstrates that the three intense low wavenumber bands of bathorhodopsin at 853, 875, and 920 cm-1 are not due to exomethylene or ring modes. Rather, assignment of these lines to out-of-plane vinyl hydrogen motions on the chain best accounts for the experimental data. Our calculations show that the intensity of these vibrations can be explained by twists of 10-30 degrees about chain single bonds. The 1100-1400-cm-1 Raman fingerprint indicates that the configuration of the double bonds is trans. This suggests that the structure of the bathorhodopsin chromophore is twisted all-trans.
mesh_terms: D000818:Animals; D002417:Cattle; D008968:Molecular Conformation; D012160:Retina / Q000032:analysis; D012168:Retinal Pigments; D012172:Retinaldehyde; D012243:Rhodopsin / Q000031:analogs & derivatives*; D013059:Spectrum Analysis, Raman
chemical_list: D012168:Retinal Pigments; C015017:bathorhodopsin; D012243:Rhodopsin; D012172:Retinaldehyde