A charge transfer process in the visual pigments.

摘要: A physical model that incorporates all the experimental information on formation of visual pigment rhodopsin is presented. The pigments consist a chromophore bound to an appropriate protein. Thus (λm 505 mμ) formed by Schiff’s base linkage C19H27CH=NH+-opsin 440 between 11-cis retinal 380 and protein opsin 280 mμ). It found there exists red shift in spectrum from base. brings explanation for this shift. shown such may be due charge transfer process (R. S. Mulliken,J. Am. Chem. Soc.,74, 811–824, 1952) electron at double bond carbons C11−C12 atomic orbital sulphur present cysteine. This provides presence SH-groups after absorption light. one-electron approximation used dipole momentμNV; hence, oscillator strengthf transitionNV estimated compared with experimentally determined extinction coefficient ∈m mixing 3.5×10−3 M 8.3×10−5 cysteine pH ranges 6 through 8. Reasonable agreement found. Solvent, concentration temperature dependence are also.