Hydrogen Reactions of Nitrogenase

Jackson, E. K.; Parshall, G. W.; Hardy, R. W. F.

doi:10.1016/s0021-9258(18)91977-0

Cited by 61 publications

(23 citation statements)

References 21 publications

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“…This reaction is important because it has attributes that are very informative about the hydrogenation reactivity of FeMo-co. The main facts for the wild-type enzyme 30,31,33,[128][129][130][131][132][133] are that the reaction is hydrogenation of D 2 , D 2 + 2H + + 2e À -2HD, and is not isotope exchange (i.e. D 2 + H 2 2 2HD), and is not catalysed isotope exchange between D 2 and water.…”

Section: Hydrogenation Of D 2 : the 'Hd Reaction'mentioning

confidence: 99%

Nitrogenase: a general hydrogenator of small molecules

Dance

2013

Chem. Commun.

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Nitrogenase naturally converts N2 to NH3, but it also hydrogenates a variety of small molecules, in many cases requiring multiple electrons plus protons for each catalytic cycle. A general mechanism, arising from many density functional calculations and simulations, is proposed to account for all of these reactions. Protons, supplied serially in conjunction with electrons to the active site FeMo-co (a CFe7MoS9 (homocitrate) cluster), generate H atoms that migrate over and populate two S and two Fe atoms in the reaction domain. The mechanistic paradigm is conceptually straightforward: substrate (on Fe) and H atoms (on S and Fe) are bound contiguously in the reaction zone, and H atoms transfer (probably with some quantum tunneling) to the substrate to form product. Details and justifications of the mechanisms for N2 and other key substrates are summarised, and the unusual structure of FeMo-co as a general hydrogenation catalyst is rationalised. Testing experiments are suggested.

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Section: Hydrogenation Of D 2 : the 'Hd Reaction'mentioning

confidence: 99%

Nitrogenase: a general hydrogenator of small molecules

Dance

2013

Chem. Commun.

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“…Carbon monoxide was inhibitory and no HD was formed in an atmosphere of argon or with acetylene or cyanide as substrates. HD formation by nitrogenase was assumed to be similar to the exchange reaction catalyzed by aryldiimine-and arylhydrazine-Pt complexes (134). Most of these results were confirmed by Kelly (144) (130,138).…”

Section: B Substrates and Kinetic Studiesmentioning

confidence: 69%

“…HD formation in extracts ofA. vinelandii was also stimulated by N 2 and had the same requirements as for N 2 fixation, i. e. ATP and reductant (134). Carbon monoxide was inhibitory and no HD was formed in an atmosphere of argon or with acetylene or cyanide as substrates.…”

Section: B Substrates and Kinetic Studiesmentioning

confidence: 88%

“…Nitrogenase catalyzes no isotope exchange, 14N 2 + 15N 2 ~ 214NlSN, indicating no initial cleavage of dinitrogen at the active site of the enzyme (11,24). Attempts to detect free intermediates have been unsuccessful, but diimine and hydrazine have repeatedly been proposed as enzyme-bound intermediary states of N 2 reduction (129,133,134). Recently Bulen (135) found that hydrazine, preferentially in its unprotonated form, is a substrate of A. vinelandii nitrogenase, lending strong support to its supposed role as an intermediate.…”

Section: B Substrates and Kinetic Studiesmentioning

confidence: 99%

“…ATP-dependent dihydrogen evolution from H3 O÷ (134) is the last in the series of twoelectron transfer reactions catalyzed by nitrogenase. In the absence of any externally added reducible substrate, all electrons are used for H 2 production.…”

Section: B Substrates and Kinetic Studiesmentioning

confidence: 99%

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