Hydrogen ion changes of rhodopsin I. Proton uptake during the metarhodopsin I 478 metarhodopsin II 308 reaction

Abstract

The hydrogen ion changes resulting from the photolysis of the rod visual pigment, rhodopsin, have been investigated. Low temperature was used to isolate the metarhodopsin I 478 to II 380 reaction of rhodopsin and indicator dye was used to simultaneously measure the hydrogen ion changes of the rhodopsin solution. The results indicate that illuminated rhodopsin takes up a proton during the metarhodopsin I 478 to II 380 reaction and releases protons at later intermediate stages. The results are consistent with data indicating p K changes of rhodopsin as the basis for the R 2 phase of the early receptor potential and hydrogen ion changes of the medium or p K changes of rhodopsin as having effects on the late receptor potential.