Catalytic Reduction of Hydrazine to Ammonia by the VFe3S4 Cubanes. Further Evidence for the Direct Involvement of the Heterometal in the Reduction of Nitrogenase Substrates and Possible Relevance to the Vanadium Nitrogenases

Malinak, Steven M.; Demadis, Konstantinos D.; Coucouvanis, D.

doi:10.1021/ja00116a017

Cited by 108 publications

(80 citation statements)

References 2 publications

(3 reference statements)

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“…Like some of the synthetic Fe/S-based clusters, which can reduce C 2 H 2 (24), H + (25), and N 2 H 4 (26) in the presence of strong reductants, the P*-cluster can catalyze the simple, two-electron reduction of the same set of substrates in reactions driven by Eu(II)-DTPA. However, this cluster can also reduce CN − and CO to hydrocarbons under ambient conditions, a catalytic property that has been attributed so far only to the isolated and protein-bound cofactors of nitrogenase (16,27,28).…”

Section: Discussionmentioning

confidence: 99%

ATP-independent substrate reduction by nitrogenase P-cluster variant

Lee

Ribbe

2012

Proc. Natl. Acad. Sci. U.S.A.

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The P-cluster of nitrogenase is largely known for its function to mediate electron transfer to the active cofactor site during catalysis. Here, we show that a P-cluster variant (designated P*-cluster), which consists of paired [Fe 4 S 4 ]-like clusters, can catalyze ATP-independent substrate reduction in the presence of a strong reductant, europium (II) diethylenetriaminepentaacetate [Eu(II)-DTPA]. The observation of a decrease of activity in the rank ΔnifH, ΔnifBΔnifZ, and ΔnifB MoFe protein, which corresponds to a decrease of the amount of P*-clusters in these cofactor-deficient proteins, firmly establishes P*-cluster as a catalytically active metal center in Eu(II)-DTPA-driven reactions. More excitingly, the fact that P*-cluster is not only capable of catalyzing the two-electron reduction of proton, acetylene, ethylene, and hydrazine, but also capable of reducing cyanide, carbon monoxide, and carbon dioxide to alkanes and alkenes, points to a possibility of developing biomimetic catalysts for hydrocarbon production under ambient conditions.N itrogenases are a family of metalloenzymes that catalyze the nucleotide-dependent reduction of dinitrogen to ammonia under ambient conditions. The best-characterized member of this enzyme family is the molybdenum (Mo)-nitrogenase of Azotobacter vinelandii, which consists of two redox-active component proteins (1). One of the proteins, termed iron (Fe) protein (encoded by nifH), is a γ 2 -dimer that contains a [Fe 4 S 4 ] cluster between the two subunits and a MgATP binding site within each subunit; the other, termed molybdenum-iron (MoFe) protein (encoded by nifDK), is an α 2 β 2 -heterotetramer that houses two complex metal clusters per αβ-dimer: the P-cluster ([Fe 8 S 7 ]), which is located at each α/β-subunit interface; and the iron-molybdenum (FeMo) cofactor, or FeMoco ([MoFe 7 S 9 C-homocitrate]), which is buried within each α-subunit (2-4). Catalysis by nitrogenase presumably involves repeated association and dissociation between the two component proteins and ATP-dependent electron transfer from the [Fe 4 S 4 ] cluster of the Fe protein, through the P-cluster, to the FeMoco of MoFe protein, where substrate reduction occurs (5).The P-cluster has long been regarded as a "capacitor" that mediates the electron transfer between the [Fe 4 S 4 ] cluster of Fe protein and the cofactor site of MoFe protein during catalysis (1). Although the question of whether the P-cluster can directly reduce substrates was raised previously, it has remained a topic of debate because of the difficulty of distinguishing the contribution of the P-cluster from that of the cofactor to catalysis. As such, MoFe protein variants carrying the P-cluster species alone need to be generated to address the catalytic capacity of P-cluster. Recent studies of the biosynthesis of nitrogenase have led to the identification of three cofactor-deficient forms of MoFe protein (Fig. 1). One form, designated ΔnifB MoFe protein, contains two intact, [Fe 8 S 7 ] P-clusters (6); another, designated ΔnifH MoFe pro...

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Section: Discussionmentioning

confidence: 99%

ATP-independent substrate reduction by nitrogenase P-cluster variant

Lee

Ribbe

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…A series of clusters, (130)(131)(132)(133)(134)(135)(136), related to this cluster were subsequently reported and the structures and reactivity of these species investigated in detail. 631,[651][652][653] Important new clusters that have been reported include two vanadium clusters with the VS 3 (132), are capable of catalyzing the reduction of hydrazine by cobaltocene/lutidine hydrochloride. 651,[653][654][655] Reduction of hydrazine to NH 3 is commonly used to document the reactivity of these clusters and for the cuboidal clusters (130)(131)(132)(133)(134)(135); the coordination of the hydrazine to the V-atom appears to be critical to its reduction.…”

Section: Clusters In Nitrogenase and Model Systems: Structure And Reamentioning

confidence: 99%

The Chemistry and Biochemistry of Vanadium and the Biological Activities Exerted by Vanadium Compounds

et al. 2004

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“…Such separations are typical for similar electronically perturbed subunits, and this behavior has been analyzed in detail in a number of cases. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]24,32,33 The electrochemical behavior of the clusters under discussion shows that these compounds retain integrity in coordinating solvents (CH3CN) and the entire cluster behaves as an entity with strongly interacting subunits. The above results are in full agreement with, and indirectly verify, the EPR observations.…”

Section: Ch3cnmentioning

confidence: 99%

Structural Characterization and Reactivity Properties of a New Class of Fe/Mo/S Double Cubanes with Mo-Bound S-.mu.2-.eta.1,O-.eta.1 Mercapto Carboxylate Ligands. New Catalysts for the Reduction of Hydrazine to Ammonia and Implications Regarding the Function of Nitrogenase

Demadis¹,

Coucouvanis²

1995

Inorg. Chem.

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The reaction of (E~N)~[MOF~~S~C~~(CL-C~~)(CH~CN)], 1, with mercapto carboxylic acids of the general type HSCH(R)COOH affords in nearly quantitative yields the novel double cubanes of the formulation [MoFe3S4Cl3(SCH(R)C0O)]z4-(R = H, mercaptoacetate, 2; R = CH3, thiolactate, 3; R = CHZCOOH, thiomalate, 4). Black crystals of (EhN)2 are monoclinic, space group C2/c, with a = 18.959(9) A, b = 12.657(7) A, c = 28.57(1) A, /3 = 98.03(4)", V = 6790(5) A3, and Z = 4. Black crystals of (EkN)3 are monoclinic, space group C2/c, with a = 16.281(5) A, b = 25.13(1) A, c = 19.019(7) A, /3 = 112.61(2)", V = 7182(4) A3, and Z = 4. The solutions of both structures were accomplished by direct methods. The refinement with full-matrix least-squares methods of 299 parameters based on 5942 unique reflections for (EbN)2 (28,,, = 45", I > 3a(l)) and of 287 parameters based on 4728 unique reflections (28,,, = 45", I > 3a(Z)) for (EkN)3 resulted in final R (R,) values of 6.09% (6.26%) and 7.00% (6.52%), respectively, for 2 and 3. In both structures anisotropic temperature factors were assigned for all the non-hydrogen atoms in the cluster tetraanions. The tetraanions in 2 or 3 are composed of two MoFe3S4 subunits linked by the deprotonated thiol groups. In 2, the mean intracubane Mo-S, Fe-S, and Fe-Cl bond distances are found at 2.356(3), 2.278(4), and 2.219(4) A, respectively. The mean Mo..*Fe and Fe-..Fe distances are found at 2.727(2) and 2.728(3) 8, respectively. Similar metric features are found for 3. Each of the two Mo atoms (separated by 3.916(3) 8, in 2 and 3.899(3) A in 3) has a distorted octahedral coordination and in addition to three p3-S2-ligands is coordinated to two p2-thiolato and a 3'-carboxylato ligands. The Mo-O(carboxy1ate) bond in 2 is 2.096(7) 8, long (2.10(1) 8, for 3), and two types of Mo-S(bridging) bond lengths are present at 2.523(3) and 2.577(3) A. The closest intercubane S * * S distance is 3.266(6) A. (Et4N)z[MoFe3S4-Cl3(Cb-cat)(CH3CN)] also reacts with thiodiglycolic acid to form the [MoFe3S4C13(00CCH2SCH2Coo)12-cluster, 5, in which the thioether dicarboxylate is coordinated to the Mo atom through its two carboxyl and thioether functionalities. Furthermore 1, reacts with 3,4-dimercaptotoluene and thiosalicylic acid to form respectively compounds 6 and 7 with the bidentate ligands bridging the two MoFesS4 subunits in a manner similar to that in 2 and 3. EPR spectra are not observed for 2-4 in CH3CN glasses at 5 K. The cyclic voltammetry of 2-4 shows multiple reductions and oxidation waves, and the two reduction waves are separated by 190-210 mV. The electrochemical data and the lack of the characteristic S = 312 EPR signal in solutions of 2-4 suggest that these molecules are electronically coupled and retain the double cubane structure in solution. Cluster 5 shows a characteristic S = 3/2 EPR signal and displays a single reduction wave at -745 mV. The reduction of hydrazine to ammonia in the presence of cobaltocene and 2,6-lutidinium chloride was catalyzed by 3. The core of the latter was found to be intact a...

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Catalytic Reduction of Hydrazine to Ammonia by the VFe3S4 Cubanes. Further Evidence for the Direct Involvement of the Heterometal in the Reduction of Nitrogenase Substrates and Possible Relevance to the Vanadium Nitrogenases

Cited by 108 publications

References 2 publications

ATP-independent substrate reduction by nitrogenase P-cluster variant

ATP-independent substrate reduction by nitrogenase P-cluster variant

The Chemistry and Biochemistry of Vanadium and the Biological Activities Exerted by Vanadium Compounds

Structural Characterization and Reactivity Properties of a New Class of Fe/Mo/S Double Cubanes with Mo-Bound S-.mu.2-.eta.1,O-.eta.1 Mercapto Carboxylate Ligands. New Catalysts for the Reduction of Hydrazine to Ammonia and Implications Regarding the Function of Nitrogenase

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