The photochemical determinants of color vision
تعليق: من مقالة عام 1992: iminium ions of omeprazole + proton pumping in the vision. وهذه المقالة تقول أيضاً the Schiff base is protonated. Retinal bound to opsins as a protonated Schiff base PSB (an iminium) absorb at different wavelengths
Retinal absorbs at 380 nm in ethanol and it blue shifts to 360 nm when it forms a Schiff base (an imine) with n-butylamine. A large red shift to 440 nm results when the Schiff base is protonated. Retinal bound to opsins as a PSB (an iminium) absorb at different wavelengths. The difference between the protein-bound PSB absorbance and 440 nm is referred to as the “opsin shift”, and represents the protein-induced change in absorption spectrum of the pigment as compared with that of the native protonated retinylidene Schiff base [41].
