Abstract
Changes in the difference spectrum of the octopus rhodopsin solution with pH 10.3 were studied at about 2°C by applying the flash photolytic technique. The main peak (about 520nm) in the difference spectrum at 10 msec after a flash coincided with the peak of the calculated difference spectrum between rhodopsin and acid metarhodopsin. It was suggested that in the octopus rhodopsin cycle the acid metarhodopsin may be a precursor of the alkaline metarhodopsin even in alkaline solution.
