@article{oai:kanazawa-u.repo.nii.ac.jp:00010853, author = {Seo, Daisuke and Kitashima, Masaharu and Sakurai, Takeshi and Inoue, Kazuhito}, issue = {1-3}, journal = {Photosynthesis Research}, month = {Dec}, note = {Ferredoxin-NAD(P)+ oxidoreductase (FNR, [EC 1.18.1.2], [EC 1.18.1.3]) from the green sulfur bacterium Chlorobaculum tepidum (CtFNR) is a homodimeric flavoprotein with significant structural homology to bacterial NADPH-thioredoxin reductases. CtFNR homologs have been found in many bacteria, but only in green sulfur bacteria among photoautotrophs. In this work, we examined the reactions of CtFNR with NADP+, NADPH, and (4S-2H)-NADPD by stopped-flow spectrophotometry. Mixing CtFNRox with NADPH yielded a rapid decrease of the absorbance in flavin band I centered at 460 nm within 1 ms, and then the absorbance further decreased gradually. The magnitude of the decrease increased with increasing NADPH concentration, but even with ~50-fold molar excess NADPH, the absorbance change was only ~45 % of that expected for fully reduced protein. The absorbance in the charge transfer (CT) band centered around 600 nm increased rapidly within 1 ms, then slowly decreased to about 70 % of the maximum. When CtFNRred was mixed with excess NADP+, the absorbance in the flavin band I increased to about 70 % of that of CtFNRox with an apparent rate of ~4 s−1, whereas almost no absorption changes were observed in the CT band. Obtained data suggest that the reaction between CtFNR and NADP+/NADPH is reversible, in accordance with its physiological function. © 2016 Springer Science+Business Media Dordrecht, Embargo period 12 months}, pages = {479--489}, title = {Kinetics of NADP+/NADPH reduction–oxidation catalyzed by the ferredoxin-NAD(P)+ reductase from the green sulfur bacterium Chlorobaculum tepidum}, volume = {130}, year = {2016} }