Trapping H-Bound to the Nitrogenase FeMo-Cofactor Active Site during H2Evolution:  Characterization by ENDOR Spectroscopy

2005 ◽  
Vol 127 (17) ◽  
pp. 6231-6241 ◽  
Author(s):  
Robert Y. Igarashi ◽  
Mikhail Laryukhin ◽  
Patricia C. Dos Santos ◽  
Hong-In Lee ◽  
Dennis R. Dean ◽  
...  
Keyword(s):  
Active Site ◽  
Endor Spectroscopy ◽  
Femo Cofactor

Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted 13C Labeling and ENDOR Spectroscopy

2021 ◽  
Author(s):  
Ana Pérez-González ◽  
Zhi-Yong Yang ◽  
Dmitriy A. Lukoyanov ◽  
Dennis R. Dean ◽  
Lance C. Seefeldt ◽  
...  
Keyword(s):  
Active Site ◽  
13C Labeling ◽  
Endor Spectroscopy ◽  
Femo Cofactor

scholarly journals Comment on “Structural evidence for a dynamic metallocofactor during N2 reduction by Mo-nitrogenase”

Science ◽  
2021 ◽  
Vol 371 (6530) ◽  
pp. eabe5481 ◽  
Author(s):  
John W. Peters ◽  
Oliver Einsle ◽  
Dennis R. Dean ◽  
Serena DeBeer ◽  
Brian M. Hoffman ◽  
...  
Keyword(s):  
Active Site ◽  
Biochemical Evidence ◽  
Mofe Protein ◽  
Femo Cofactor

Kang et al. (Reports, 19 June 2020, p. 1381) report a structure of the nitrogenase MoFe protein that is interpreted to indicate binding of N2 or an N2-derived species to the active-site FeMo cofactor. Independent refinement of the structure and consideration of biochemical evidence do not support this claim.

How an Enzyme Tames Reactive Intermediates:  Positioning of the Active-Site Components of Lysine 2,3-Aminomutase during Enzymatic Turnover As Determined by ENDOR Spectroscopy

2006 ◽  
Vol 128 (31) ◽  
pp. 10145-10154 ◽  
Author(s):  
Nicholas S. Lees ◽  
Dawei Chen ◽  
Charles J. Walsby ◽  
Elham Behshad ◽  
Perry A. Frey ◽  
...  
Keyword(s):  
Active Site ◽  
Reactive Intermediates ◽  
Endor Spectroscopy

scholarly journals Electron Redistribution within the Nitrogenase Active Site FeMo-Cofactor During Reductive Elimination of H2 to Achieve N≡N Triple-Bond Activation

2020 ◽  
Vol 142 (52) ◽  
pp. 21679-21690
Author(s):  
Dmitriy A. Lukoyanov ◽  
Zhi-Yong Yang ◽  
Dennis R. Dean ◽  
Lance C. Seefeldt ◽  
Simone Raugei ◽  
...  
Keyword(s):  
Active Site ◽  
Triple Bond ◽  
Bond Activation ◽  
Reductive Elimination ◽  
Femo Cofactor

scholarly journals Catalysis-dependent selenium incorporation and migration in the nitrogenase active site iron-molybdenum cofactor

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Thomas Spatzal ◽  
Kathryn A Perez ◽  
James B Howard ◽  
Douglas C Rees
Keyword(s):  
Active Site ◽  
Azotobacter Vinelandii ◽  
Protein A ◽  
Reduction Activity ◽  
Starting Point ◽  
Activated State ◽  
Selective Incorporation ◽  
Femo Cofactor ◽  
And Migration ◽  
Biological Nitrogen

Dinitrogen reduction in the biological nitrogen cycle is catalyzed by nitrogenase, a two-component metalloenzyme. Understanding of the transformation of the inert resting state of the active site FeMo-cofactor into an activated state capable of reducing dinitrogen remains elusive. Here we report the catalysis dependent, site-selective incorporation of selenium into the FeMo-cofactor from selenocyanate as a newly identified substrate and inhibitor. The 1.60 Å resolution structure reveals selenium occupying the S2B site of FeMo-cofactor in the Azotobacter vinelandii MoFe-protein, a position that was recently identified as the CO-binding site. The Se2B-labeled enzyme retains substrate reduction activity and marks the starting point for a crystallographic pulse-chase experiment of the active site during turnover. Through a series of crystal structures obtained at resolutions of 1.32–1.66 Å, including the CO-inhibited form of Av1-Se2B, the exchangeability of all three belt-sulfur sites is demonstrated, providing direct insights into unforeseen rearrangements of the metal center during catalysis.

Hydrogenases in the "active" state: determination of g-matrix axes and electron spin distribution at the active site by 1H ENDOR spectroscopy

2001 ◽  
Vol 7 (1-2) ◽  
pp. 177-194 ◽  
Author(s):  
Arnd Müller ◽  
Irene Tscherny ◽  
Reinhard Kappl ◽  
Claude E. Hatchikian ◽  
Jürgen Hüttermann ◽  
...  
Keyword(s):  
Electron Spin ◽  
Active Site ◽  
Active State ◽  
Spin Distribution ◽  
Endor Spectroscopy ◽  
State Determination

scholarly journals Evidence for a dynamic role for homocitrate during nitrogen fixation: the effect of substitution at the α-Lys426 position in MoFe-protein of Azotobacter vinelandii

2006 ◽  
Vol 397 (2) ◽  
pp. 261-270 ◽  
Author(s):  
Marcus C. Durrant ◽  
Amanda Francis ◽  
David J. Lowe ◽  
William E. Newton ◽  
Karl Fisher
Keyword(s):  
Active Site ◽  
Ring Opening ◽  
Azotobacter Vinelandii ◽  
Chelate Ring ◽  
Wild Type ◽  
Biologically Relevant ◽  
Mofe Protein ◽  
Key Players ◽  
Femo Cofactor ◽  
The Subject

Although it is generally accepted that the active site of nitrogenase is located on the FeMo-cofactor, the exact site(s) of N2 binding and reduction remain the subject of continuing debate, with both molybdenum and iron atoms being suggested as key players. The current consensus favours binding of acetylene and some other non-biologically relevant substrates to the central iron atoms of the FeMo-cofactor [Dos Santos, Igarashi, Lee, Hoffman, Seefeldt and Dean (2005) Acc. Chem. Res. 38, 208–214]. The reduction of N2 is, however, a more demanding process than reduction of these alternative substrates because it has a much higher activation energy and does not bind until three electrons have been accumulated on the enzyme. The possible conversion of bidentate into monodentate homocitrate on this three electron-reduced species has been proposed to free up a binding site for N2 on the molybdenum atom. One of the features of this hypothesis is that α-Lys426 facilitates chelate ring opening and subsequent orientation of the monodentate homocitrate by forming a specific hydrogen bond to the homocitrate -CH2CH2CO2− carboxylate group. In support of this concept, we show that mutation of α-Lys426 can selectively perturb N2 reduction without affecting acetylene reduction. We interpret our experimental observations in the light of a detailed molecular mechanics modelling study of the wild-type and altered MoFe-nitrogenases.

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