On the Charge Transfer Model for Visual Pigments. I

抄録

Regarding unprotonated retinal Schiff-base as donor D and the phenol group of tyrosine as acceptor A, the charge-transfer model proposed by Akhtar et al. for visual pigments is examined according to our previous formulations and parametrization for π-electron systems. The ball-socket linkage model by Hooper and Buckser, which can be regarded as a kind of charge-transfer model, is also examined in the same way, regarding the charge distribution on the amino group as a positive point-charge. It is thus shown that these two models cannot explain the remarkable red-shift of λ_max observed for the retinal in visual pigments.