Fukuda Yohta, Tse Ka Man, Kado Yuji, Mizohata Eiichi, Matsumura Hiroyoshi, Inoue Tsuyoshi
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Interdisciplinary Program for Biomedical Sciences, Institute for Academic Initiatives, Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Biochem Biophys Res Commun. 2015 Aug 21;464(2):622-8. doi: 10.1016/j.bbrc.2015.07.025. Epub 2015 Jul 9.
Bifunctional copper nitrite reductase (CuNIR) catalyzes nitrite reduction to nitric oxide and dioxygen reduction to hydrogen peroxide. In contrast to the well-researched nitrite reduction mechanism, the oxygen reduction mechanism in CuNIR has been totally unknown, because mononuclear copper-oxygen complexes decompose so readily that their visualization has been challenging. Here, we provide spectroscopic evidence that a foreign ligand binds to the catalytic copper (T2Cu) site of CuNIR, and determine CuNIR structures displaying a diatomic molecule on T2Cu. This unknown ligand can be interpreted as dioxygen and may provide insights into the oxygen reduction mechanism of CuNIR.
