Effect of Mn ion on the visible light induced water oxidation activity of photosynthetic organ grana from spinach

To develop the visible light induced hydrogen and oxygen production based on the water photolysis, 2,6-dichloroindophenol (DCIP) reduction based on the photoinduced water oxidation with oxygen evolved centre (OEC) of PSII in photosynthesis organ, grana from spinach was studied. It noted that manganese cluster consisted of four manganese ions in OEC, and the role and effect of manganese(II) and (III) ions on the DCIP reduction were investigated. By addition of manganese(III) acetate up to 80 μmol dm−3, the concentration of the reduced DCIP with irradiation was increased compared with the system in the absence of manganese(III) acetate. The activity of DCIP reduction in the presence of 80 μmol dm−3 manganese(III) acetate was 4.7 times higher than that in the absence of manganese(III) acetate. In contrast, the concentration of the reduced DCIP with irradiation was increased by addition of manganese(II) acetate up to 40 μmol dm−3 compared with the system in the absence of manganese(II) acetate. These results show that the DCIP photoreduction with grana was promoted by addition of manganese(III) or (II) ion.