Figure 22.14  The structure and function of ferredoxin-NADP+ reductase. (A) The structure of ferredoxin-NADP+ reductase is shown in yellow. This enzyme accepts electrons, one at a time, from ferredoxin (shown in orange). (B) Ferredoxin-NADP+ reductase first accepts two electrons and two protons from two molecules of reduced ferredoxin (Fdred) to form FADH2, which then transfers two electrons and a proton to NADP+ to form NADPH.