Arnon-Buchanan Cycle

The Reductive Citric Acid Cycle (Arnon-Buchanan Cycle)... 

Buchanan BB, Arnon DI. 1990. A reverse KREBS cycle in photosynthesis consensus at last. Photosyn Res 24 47-53. 

Evans MCW, Buchanan BB, Arnon DI. 1966. A new ferredoxin-dependent carbon reduction cycle in a photosynthetic bacterium. Proc Natl Acad Sci USA 55 928-34. 

Bacterial ferredoxins function primarily as electron carriers in ferredoxin-mediated oxidation reduction reactions. Some examples are reduction of NAD, NADP, FMN, FAD, sulfite and protons in anaerobic bacteria, CO -fixation cycles in photosynthetic bacteria, nitrogen fixation in anaerobic nitrogen fixing bacteria, and reductive carboxylation of substrates in fermentative bacteria. The roles of bacterial ferredoxins in these reactions have been summarized by Orme-Johnson (2), Buchanan and Arnon (3), and Mortenson and Nakos (31). 

Evans, Buchanan, and Arnon (41a) have recently found that the ferredoxin-dependent pyruvate and a-ketoglutarate synthesizing reactions function in a new carbon cycle for the photosynthetic fixation of C02. The new cycle was named the reductive carboxylic acid cycle, and apart from pyruvate and a-ketoglutarate synthases, it includes certain of the enzymes associated with Krebs citric acid cycle, operating in the synthetic direction. Photoreduced ferredoxin and ATP, formed by photo-... 

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