ABSTRACT
Bathorhodopsin-rhodopsin difference spectra of native 11-cis-rhodopsin and regenerated 9-cis-rhodopsin were measured at room temperature with a double-beam laser spectrophotometer after excitation at 532 nm. A detailed analysis of data obtained at 85 psec after excitation suggests that the bathorhodopsins generated from 11-cis- and 9-cis-rhodopsin differ in their extinction coefficients and that their absorption maxima are shifted in wavelength by about 10 nm from one another. The ratio of quantum yields for photochemical production of the 11-cis-bathorhodopsin and the 9-cis-bathorhodopsin approximates 1. Implications that the early photochemical processes in vision are more complex than previously considered are explored.
Subject(s)
Retinal Pigments/metabolism , Rhodopsin/metabolism , Vision, Ocular , Animals , Cattle , Light , Rhodopsin/analogs & derivatives , Rhodopsin/radiation effects , Spectrum Analysis , Structure-Activity RelationshipABSTRACT
The formation of Metarhodopsin II, measured spectroscopically in the excised bovine retina at 37 degrees C, can be described by the sum of two exponentials. The R2 response of a simultaneously recorded early receptor potential can be matched by the difference of two weighted exponentials, whose time constants are identical to those obtained for the spectroscopic signal.
