Metabolic Interactions between Spinach Leaf Nitrite Reductase and Ferredoxin-NADP Reductase: Competition for Reduced Ferredoxin

Steady state rates of NADP reduction decline upon commencement of nitrite reduction in reconstituted chloroplast preparations. Similarly, steady state rates of nitrite reduction are lower, but not zero, during concurrent NADP reduction. These results imply that competition for substrate occurs and suggest that nitrite reduction can successfully compete for reduced ferredoxin, even at high rates of NADP reduction.