Nitrite Reduction by Isolated Chloroplasts in Light

Abstract

Losada, Whatley and Arnon1 have shown that non-cyclic photo-phosphorylation in chloroplasts is the result of two independent light reactions: (a) a photo-oxidation of water, which is absent in photosynthetic bacteria; (b) a non-cyclic photo-phosphorylation of the bacterial type2. By inhibiting1 or destroying3 the system involved in the photo-oxidation of water, it has been possible to couple the light-dependent oxidation of certain suitable electron donors (ascorbate, cystein) with the photoreduction of such low-potential electron carriers as methyl or benzyl viologen4. These artificial co-factors can be used with the aid of bacterial hydrogenase either for the fixation or for the dark and light evolution of hydrogen gas2,4,5. Mortenson et al.6 and Paneque and Arnon3 have shown that ferredoxin is the natural electron transferring factor involved in these reactions. According to Tagawa and Arnon7, the pyridine nucleotide reducing factors previously isolated and purified from either green plants8,9 or photosynthetic bacteria1 are ferredoxins.