. Biological structure and function; proceedings. Biochemistry; Cytology. 346 DANIEL I. ARNON These findings are in agreement with the recent resuhs of Wessels [54], Jagendorf and Avron [55] and Nakamoto, Krogmann, and Vennesland [56], that photosynthetic phosphorylation with suboptimal amounts of cofactors is oxygen-dependent but becomes oxygen-independent at higher concentrations of cofactors. In charting their subsequent investigations Arnon and his associates laid special stress on the anaerobic photosynthetic phosphorylation which proceeds in isolated chloroplasts at optimal catalytic con
. Biological structure and function; proceedings. Biochemistry; Cytology. 346 DANIEL I. ARNON These findings are in agreement with the recent resuhs of Wessels [54], Jagendorf and Avron [55] and Nakamoto, Krogmann, and Vennesland [56], that photosynthetic phosphorylation with suboptimal amounts of cofactors is oxygen-dependent but becomes oxygen-independent at higher concentrations of cofactors. In charting their subsequent investigations Arnon and his associates laid special stress on the anaerobic photosynthetic phosphorylation which proceeds in isolated chloroplasts at optimal catalytic concentrations of FMN and vitamin K. They considered this type more fundamental to photosynthesis in general than the oxygen-catalyzed type because it would also apply to bacterial photosynthesis, in which oxygen cannot be involved. INTENSE LIOIT ond HIGH CHLOROPHYLL. 0-003 001 0-OS 0-1 0-3 10 //moles vit. K3 added 0-003 001 0-OS 0-1 0-3 10 //moles FMN added Fig. 3. Effect of vitamin K3 (2-methyl-i,4-naphthoquinone) and FMN con- centration on cyclic photophosphorylation by spinach chloroplasts in nitrogen and air at high light intensity. The reaction mixture (3 ml. final volume) included chloroplast fragments (Cij) containing i â 5 mg. chlorophyll; and in micromoles: tris buffer pH 8 ⢠3, 80; K2H32PO4, 20; ADP, 20; MgS04, 5 ; and TPN, o ⢠3 (only in the FMN series). FMN and vitamin K3 were added as indicated. The reaction was run for 5 min. at an illumination of 50 000 Lux (Tsujimoto, Hall, and Arnon [92]; Arnon, Whatley, and Allen, unpublished data, 1954). Soon after the discovery of photosynthetic phosphorylation in isolated chloroplasts, Frenkel [57] reported a similar phenomenon in the photo- synthetic bacterium Rhodospirilhnn ruhrum. Although Frenkel suggested that the light-induced ATP formation in bacterial preparations was similar to that in chloroplasts, the similarity seemed uncertain at first, because Frenkel's photophosphorylation system, which was a sonic macer
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