化学
固氮酶
硫黄
辅因子
星团(航天器)
钼
铁硫簇
光化学
立体化学
作者
Kazuki Tanifuji,Andrew J. Jasniewski,David Villarreal,Martin T. Stiebritz,Chi Chung Lee,Jarett Wilcoxen,Yasuhiro Okhi,Ruchira Chatterjee,Isabel Bogacz,Junko Yano,Jan Kern,Britt Hedman,Keith O. Hodgson,R. David Britt,Yilin Hu,Markus W. Ribbe
标识
DOI:10.1038/s41557-021-00799-8
摘要
Molybdenum nitrogenase catalyses the reduction of N2 to NH3 at its cofactor, an [(R-homocitrate)MoFe7S9C] cluster synthesized via the formation of a [Fe8S9C] L-cluster prior to the insertion of molybdenum and homocitrate. We have previously identified a [Fe8S8C] L*-cluster, which is homologous to the core structure of the L-cluster but lacks the 'ninth sulfur' in the belt region. However, direct evidence and mechanistic details of the L*- to L-cluster conversion upon 'ninth sulfur' insertion remain elusive. Here we trace the 'ninth sulfur' insertion using SeO32- and TeO32- as 'labelled' SO32-. Biochemical, electron paramagnetic resonance and X-ray absorption spectroscopy/extended X-ray absorption fine structure studies suggest a role of the 'ninth sulfur' in cluster transfer during cofactor biosynthesis while revealing the incorporation of Se2-- and Te2--like species into the L-cluster. Density functional theory calculations further point to a plausible mechanism involving in situ reduction of SO32- to S2-, thereby suggesting the utility of this reaction to label the catalytically important belt region for mechanistic investigations of nitrogenase.
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