Abstract
Picosecond and nanosecond spectroscopic studies on the primary processes of chromoproteins with retinal (retinoid proteins) are reviewed. The retinoid proteins described here are a visual pigment rhodopsin and two analogues, bacteriorhodopsin and sensory rhodpsin. Bacteriorhodopsin and sensory rhodopsin are a light-driven proton pump and a photoreceptor of the phototaxis of halobacteria. There are the following common charac-teristics in their photo-induced reactions. (i) Photoreactions are initiated by photoisomerizations of retinals and followed by sequential thermal reactions. (ii) In the early stage red-shifted intermediates are formed. They are converted to more blue-shifted intermediates in the sequential reactions.
