Escherichia coli ferredoxin-NADP+ reductase and oxygeninsensitive nitroreductase are capable of functioning as ferric reductase and of driving the Fenton reaction

Kouji Takeda, Junichi Sato, Kazuyuki Goto, Takanori Fujita, Toshihiro Watanabe, Mitsuru Abo, Etsuro Yoshimura, Junichi Nakagawa, Akira Abe, Shinji Kawasaki, Youichi Niimura

研究成果: Article

15 引用 (Scopus)

抜粋

Two free flavin-independent enzymes were purified by detecting the NAD(P)H oxidation in the presence of Fe(III)-EDTA and t-butyl hydroperoxide from E. coli. The enzyme that requires NADH or NADPH as an electron donor was a 28 kDa protein, and N-terminal sequencing revealed it to be oxygen-insensitive nitroreductase (NfnB). The second enzyme that requires NADPH as an electron donor was a 30 kDa protein, and N-terminal sequencing revealed it to be ferredoxin-NADP+ reductase (Fpr). The chemical stoichiometry of the Fenton activities of both NfnB and Fpr in the presence of Fe(III)-EDTA, NAD(P)H and hydrogen peroxide was investigated. Both enzymes showed a one-electron reduction in the reaction forming hydroxyl radical from hydrogen peroxide. Also, the observed Fenton activities of both enzymes in the presence of synthetic chelate iron compounds were higher than their activities in the presence of natural chelate iron compounds. When the Fenton reaction occurs, the ferric iron must be reduced to ferrous iron. The ferric reductase activities of both NfnB and Fpr occurred with synthetic chelate iron compounds. Unlike NfnB, Fpr also showed the ferric reductase activity on an iron storage protein, ferritin, and various natural iron chelate compounds including siderophore. The Fenton and ferric reductase reactions of both NfnB and Fpr occurred in the absence of free flavin. Although the kcat/Km value of NfnB for Fe(III)-EDTA was not affected by free flavin, the kcat/Km value of Fpr for Fe(III)-EDTA was 12-times greater in the presence of free FAD than in the absence of free FAD.

元の言語English
ページ(範囲)727-737
ページ数11
ジャーナルBioMetals
23
発行部数4
DOI
出版物ステータスPublished - 1 8 2010

これを引用

Takeda, K., Sato, J., Goto, K., Fujita, T., Watanabe, T., Abo, M., Yoshimura, E., Nakagawa, J., Abe, A., Kawasaki, S., & Niimura, Y. (2010). Escherichia coli ferredoxin-NADP+ reductase and oxygeninsensitive nitroreductase are capable of functioning as ferric reductase and of driving the Fenton reaction. BioMetals, 23(4), 727-737. https://doi.org/10.1007/s10534-010-9339-8