Chemical probes of nitrogenase. 1. Cyclopropene. Nitrogenase-catalyzed reduction to propene and cyclopropane

McKenna, Charles E.; McKenna, M. C.; Higa, Melvin T.

doi:10.1021/ja00431a059

Cited by 25 publications

(18 citation statements)

References 2 publications

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“…For example, cyclopropene (Table 1) can undergo reduction to cleave the single bond forming propene and reduction of the double bond forming cyclopropane [48,53,54]. The production of both 1,3- and 2,3-dideuteropropene when the reaction is run in D 2 O indicated that there must be an isomerization process of the intermediate derived from the single bond cleavage [48].…”

Section: Early C-compounds and Nitrogenasementioning

confidence: 99%

Nitrogenase reduction of carbon-containing compounds

Seefeldt

Yang

Duval

et al. 2013

Biochimica et Biophysica Acta (BBA) - Bioenergetics

100

104

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Nitrogenase is an enzyme found in many bacteria and archaea that catalyzes biological dinitrogen fixation, the reduction of N2 to NH3, accounting for the major input of fixed nitrogen into the biogeochemical N cycle. In addition to reducing N2 and protons, nitrogenase can reduce a number of small, non-physiological substrates. Among these alternative substrates are included a wide array of carbon containing compounds. These compounds have provided unique insights into aspects of the nitrogenase mechanism. Recently, it was shown that carbon monoxide (CO) and carbon dioxide (CO2) can also be reduced by nitrogenase to yield hydrocarbons, opening new insights into the mechanism of small molecule activation and reduction by this complex enzyme as well as providing clues for the design of novel molecular catalysts.

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Section: Early C-compounds and Nitrogenasementioning

confidence: 99%

Nitrogenase reduction of carbon-containing compounds

Seefeldt

Yang

Duval

et al. 2013

Biochimica et Biophysica Acta (BBA) - Bioenergetics

100

104

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“…Mo-nitrogenase contains two proteins designated as the [28]. It has been demonstrated that cyclopropene could undergo reduction by Mo-nitrogenase to cleave the single bond forming propene [29]. It has also been shown that nitrogenase can reduce both C=S and C=O bonds, catalyzing the reduction of CO 2 to CH 4 [22,23].…”

Section: Resultsmentioning

confidence: 99%

Microbial reduction of graphene oxide by Azotobacter chroococcum

Chen

Niu

Tian

et al. 2017

Chemical Physics Letters

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We report an eco-friendly route for the reduction of graphene oxide (GO) by Azotobacter chroococcum at room temperature. Examinations using X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy indicate the formation of reduced graphene oxide (rGO) with a low degree of agglomeration. Quantitative analyses of electron diffraction data show that the produced rGO consists of single-layer sheets with a random stacking. It is suggested that the GO was reduced directly by the nitrogenase via sequential additions of electrons and protons followed by dehydration. This approach avoids the use of toxic chemical agents and also reduces the agglomeration of rGO.

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“…Allene and methylacetylene were CP (chemically pure) products from Matheson and were purified by lowpressure distillation before use. Cyclopropene was prepared and purified by methods described elsewhere (7) Product Isolation. The gas portion of each assay bottle was transferred into a 30-ml plastic syringe by gas-liquid displacement using a saturated Na2SO4 solution, then separated by preparative GC.…”

Section: Experimental Partmentioning

confidence: 99%

Low stereoselectivity in methylacetylene and cyclopropene reductions by nitrogenase.

McKenna¹,

McKenna²,

Huang³

1979

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

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The stereochemistry of reductions catalyzed by nitiogenase in 2H20 has been investigated by using allene, methylacetylene, and cyclopropene as substrates. Deuterium labeling patterns in the reduction products were determined by mass spectroscopy, infrared s ectroscopy, 2H-decoupled 220-MHz 1H NMR, and IH-decoupfd 30.7-MHz 2H NMR. Reduction of allene gave pure [2,3-H2lpropene Stereochemistry is a characteristic feature of many enzymemediated reactions that often provides mechanistically valuable clues concerning active site-substrate interactions. Nitrogenase catalyzes the ATP-dependent reduction of N2 to NH3, possibly via enzyme-bound N2H2 and N2H4 intermediates (1); stereochemistry arising from geometrical isomerism is possible only with the first postulated intermediate, diazene. The instability of free diazene (cis or trans) has forestalled a direct demonstration of substrate behavior, and it has not proven detectable during nitrogenase-catalyzed N2 fixation. Among the various adventitious nitrog'enase substrates (1), C2H2 has been used to explore reduction stereochemistry. Exposure of C2H2 to active nitrogenase/2H20 assay mixtures reportedly has resulted predominantly or exclusively in formation of [cis-1,2-2H21C2H4 (2-4). A primary kinetic isotope effect has not been observed in these 2H20 reductions. This finding has been cited in support of a concerted transfer of two protons and two electrons to substrate, possibly involving a specifically positioned pair of acids derived from the enzyme protein residues (5). Because of its high symmetry (D0h), C2H2 is a comparatively insensitive stereochemical probe: a nonspecific addition of exterior solvent protons to C2H2 bound to an active site metal center, or other mechanisms, arguably could account for the observed preferential formation of the cis-alkene isomer. Important advantages of C2H2 as a substrate are that it interacts efficiently with nitrogenase [Km(C2H2) Km(N2)] and that it gives a conveniently analyzed product. There are apparent differences in the kinetic behavior of C2H2 and N2, suggestive of incomplete equivalence between the two substrates (6).We have demonstrated (7) that cyclopropene is a substrate of nitrogenase, being reduced to a mixture of propene and cyclopropane whose proportions are remarkably insensitive (8) to in vivo vs. in vitro assay. Cyclopropene is a reversible inhibitor of nitrogenase N2 reduction and is reduced with a Km value as low as that of N2 or C2H2 (8). In contrast, the acyclic C3H4 isomers allene and methylacetylene are poor substrates, judging from their large Km values (9). Acyclic alkenes such as C2H4 or propene do not show detectable substrate activity with nitrogenase (1). The lower symmetry (C2v), rigid ring structure, and structurally differing products available with cyclopropene suggest that it might be useful as a stereochemical probe for reduction by nitrogehase in 2H20. We note that only three We report here product characterization studies comparing 2H20/nitrogenase reductions of all three C3H4 isom...

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Chemical probes of nitrogenase. 1. Cyclopropene. Nitrogenase-catalyzed reduction to propene and cyclopropane

Cited by 25 publications

References 2 publications

Nitrogenase reduction of carbon-containing compounds

Nitrogenase reduction of carbon-containing compounds

Microbial reduction of graphene oxide by Azotobacter chroococcum

Low stereoselectivity in methylacetylene and cyclopropene reductions by nitrogenase.

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