From Bacillus subtilis cell extracts, ferredoxin-NADP reductase (FNR) was purified to homogeneity and found to be the yumC gene product by N-terminal amino acid sequencing. YumC is a ~94 kDa homodimeric protein with one molecule of non-covalently bound FAD per subunit. In a diaphorase assay with 2,6-dichlorophenol-indophenol as an electron acceptor, the affinity to NADPH was much higher than to...