抄録
A concurrent microchemical and topochemical study of DAB* oxidation by isolated chloroplasts of Vicia faba under illumination was carried out. A new method for the quantification of the oxidation product of DAB was explored. The microchemical analysis by this method revealed that the photosystem responsible for the DAB oxidation was the PS-I. It also proved that endogenous active oxygen in the chloroplasts played only a little role in the oxidation. The topochemical analysis revealed that both the grana and the stroma membrane were positive in DAB photooxidation. The densitometric traces across the grana membranes in both surface and side views proved effective in locating the precise reaction sites. The partition layer showed a high degree of positive reaction. The thylakoid membrane proper also contained particles of positive reaction. The positive site extended to the thylakoid loculus to form protrusions. These results are in harmony with the localization of the PS-I complex particles on the PF face side of the thylakoid membrane as revealed by the freeze fracture technique.
