title: Resonance Raman studies of bovine metarhodopsin I and metarhodopsin II.
abstract: The resonance Raman spectra of bovine metarhodopsin I and metarhodopsin II have been measured. The spectra are compared with model chromophore resonance Raman data. It was found that metarhodopsin I is linked to opsin via a protonated Schiff base linkage, whereas metarhodopsin II is linked by an unprotonated Schiff base. A recent suggestion that the chromophore of metarhodopsin II is retinal is explicitly disproved. The chromophores of both metarhodopsins are found to have an essentially all-trans conformation. The basic mechanism for color regulation in both forms appears to be electron delocalization. The data tend to support the model of cis-trans isomerization as the primary mechanism for vision. Also, the conclusions and inferences of this work on energy uses and storage by rhodopsin in neural generation are discussed.
mesh_terms: D000818:Animals; D002417:Cattle; D004735:Energy Transfer; D010777:Photochemistry; D011487:Protein Conformation; D012168:Retinal Pigments / Q000031:analogs & derivatives; D012243:Rhodopsin / Q000031:analogs & derivatives; D012545:Schiff Bases; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism
chemical_list: D012168:Retinal Pigments; D012545:Schiff Bases; C013110:metarhodopsins; D012243:Rhodopsin