Abstract
1. The O2 uptake by rhodopsin solution was demonstrated with the Warburg constant volume respirometer. The values of QO2 of non-bleached and bleached rhodopsin were 12.56 and 2.52 respectively.
2. Following the addition of metal inhibitors it was demonstrated that the O2 uptake by the rhodopsin solution might be attributed to the presence of nonheme iron in the solution.
3. It was demonstrated that no cytochrome oxidase activity was found in rhodopsin solution.
4. At the first stage, molecular oxygen was taken up by non-heme iron which might exist on the surface of the rhodopsin molecule. Then the oxygen was transferred to phospholipid which is a component of the rhodopsin molecule, so that the oxygen was not saturated for hours in vitro. 5. The non respiratory oxygen uptake by rod outer segments, reported in the previous paper, might be attributable to the function of the rhodopsin molecule.
