Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the "9th Sulfur". (5th September 2019)

• Record Type: Journal Article
• Authors: Jasniewski, Andrew J.; Wilcoxen, Jarett; Tanifuji, Kazuki; Hedman, Britt; Hodgson, Keith O.; Britt, R. David; Hu, Yilin; Ribbe, Markus W.
• Is Part Of: Angewandte Chemie. Volume 131:Number 41(2019)
• Page Start: 14845
• Page End: 14849
• Publication Date: 2019-09-05
• Subjects: Bioanorganische Chemie -- Eisen-Schwefel-Cluster -- NifB -- Metalloenzyme -- Nitrogenase; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201907593
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Nitrogenases catalyze the reduction of N2 to NH4 + at its cofactor site. Designated the M‐cluster, this [MoFe7 S9 C( R ‐homocitrate)] cofactor is synthesized via the transformation of a [Fe4 S4 ] cluster pair into an [Fe8 S9 C] precursor (designated the L‐cluster) prior to insertion of Mo and homocitrate. We report the characterization of an eight‐iron cofactor precursor (designated the L*‐cluster), which is proposed to have the composition [Fe8 S8 C] and lack the "9 th sulfur" in the belt region of the L‐cluster. Our X‐ray absorption and electron spin echo envelope modulation (ESEEM) analyses strongly suggest that the L*‐cluster represents a structural homologue to the l ‐cluster except for the missing belt sulfur. The absence of a belt sulfur from the L*‐cluster may prove beneficial for labeling the catalytically important belt region, which could in turn facilitate investigations into the reaction mechanism of nitrogenases. Abstract : Auf der Gürtellinie : Ein rein Eisen‐haltiger Nitrogenase‐Cofaktor‐Vorläufer (L*‐Cluster genannt) wurde spektroskopisch charakterisiert. Der Strukturvorschlag liefert die Zusammensetzung [Fe8 S8 C], womit der „9. Schwefel" in der Gürtelregion nicht vorhanden wäre. Die Abwesenheit dieses Schwefels kann günstig für die Markierung dieser Position für mechanistische Nitrogenase‐Studien sein.