Hydrogenase mimic

Last updated

A hydrogenase mimic or bio-mimetic is an enzyme mimic of hydrogenases.

Contents

Bio-mimetic compounds inspired in hydrogenases

One of the more interesting applications of hydrogenases is to produce hydrogen, due its capacity to catalyze its redox reaction:

2H+ + 2e ----> H2

In the field of hydrogen production, the incorporation of chemical compounds in electrochemical devices to produce molecular hydrogen has been a topic of huge interest in the recent years due to the possibility of using hydrogen as a replacement of the fossil fuels as an energetic carrier. This approach of using materials inspired by natural models to do the same function as their natural counterparts is called bio-mimetic approach. Nowadays this approach has received a big impulse due to the availability of high-resolution crystal structures of several hydrogenases obtained with different techniques. The technical details of these hydrogenases are stored in electronic databases at disposition to who may be interested.

This information has allowed scientists to determine the important parts of the enzyme necessary to catalyze the reaction and determine the pathway of the reaction in a very detailed way. Which allow to have a very good comprehension of what is necessary to catalyze the same reaction using artificial components.

Examples of bio-mimetic compounds inspired in hydrogenase

Several studies have demonstrated the possibility to develop chemical cells inspired by biological models to produce molecular hydrogen, for example: Selvaggi et al. [1] explored the possibility to use energy captured by the PSII, developing for that goal, an organic-inorganic hybrid system replacing the PSII protein complex by microspheres of TiO2 a photo-inducible compound. In order to get the hydrogen production, the TiO2 microspheres were covered with hydrogenases extracted from the marine thermophile Pyrococcus furiosus , in that way the energy of the light was captured by the TiO2 microspheres and used to generate protons and electrons from water with the subsequent production of 29 µmol de H2 hour−1.

The obtained results from immobilization of hydrogenases on the surface of electrodes have demonstrated the viability of incorporating these enzymes in electrochemical cells, due to their ability to produce gaseous hydrogen through a redox reaction. (Hallenbeck and Benemann [2] ). This opens the possibility of using biomimetic compounds in electrodes to generate hydrogen.

Until the present day several bio-mimetic compounds have been developed: Collman et al. [3] produced ruthenium porphyrins, furthermore of the bio-mimetic compounds published by the research teams of Rauchfuss, Darensbourg and Pickett (in Artero and Fontecave [4] ) who developed bio-mimetic compounds of the [Fe] hydrogenase. More recently Manor and Rauchfuss [5] presented a very interesting mimic compound based in the [NiFe] hydrogenase with bidirectional properties, this compound has the characteristic that it carries two borane protected cyanide ligands at the iron atom. Some works about bio-mimetic compounds of hydrogenases are summarized in table 1.

Biomimetic compoundHydrogen productionElectron donorReference
Bis(thiolate)-bridged diiron ([2Fe2S])0.22 (30%)Kluwer et al. [6]
2-aza-1,3-dithiol

Bridged Fe-dimer

complexes

Sun et al. [7]
[MnRe(CO)6(m-S2CPR3)]Zhao et al. [8]
Polymer (Poly-{Fe2}) functionalized with {Fe2(CO)6}Liu et al. [9]
Diiron dithiolate complexes with 3,7-diacetyl-1,3,7-triaza-5 phosphabicyclo[3.3.1]nonane ligand(s)Na et al. [10]
Enzyme electrodes, [NiFe] hydrogenases9-30 (nmol min−1)methyl viologen or waterMorozov et al. [11]
Hydrogenase in a two-compartment proton-exchange-membrane (PEM)Sodium dithionite (SD)Oh et al. [12]
Pt-clusters deposited on the interior of a heat shock protein cage architecture268 H2/Pt/min,methyl viologenVarpness. et al. [13]
Hydrogenase immobilization, on porous pyrolytic carbon paper (PCP) and packed graphite

columns (PGC)

Johnston et al. [14]
Fe2(CO)6(l-ADT) (ADT = azadithiolate)Constable et al. [15]
[Fe2(CO)6(H3COCH(CH2S)2)] and [Fe2(CO)6(HOC(CH3)(CH2S)2)].Apfel et al. [16]
Dithiolate-bridged hexacarbonyldiiron complexGoff et al. [17]
m-(SCH(CH3)CH2S)eFe2(CO)6,

m-(SCH(CH3)CH(CH3)S)eFe2(CO)6, m-(SCH2CH(CH2OH)S)eFe2(CO)6,

Donovan et al. [18]
A series of mononuclear NiII and binuclear NiIINiII macrocyclic complexes: [NiLi(H2O)] 2H2OMartin et al. [19]
[Fe2(CO)3(l-pdt){l,g2-Ph2PCH2CH2P(Ph)CH2CH2PPh2}]Hogarth and Richards [20]
Di-iron model complexes (l-pdt)Fe2(CO)5L with L = pyridine ligands, e.g. py (A), etpy (B), btpy (C),Zhang et al. [21]

Table 1. Bio-mimetic compounds of hydrogenases

However, obtaining bio-mimetic compounds able to hydrogen production on an industrial scale still is elusive. For that reason, the research of this topic is a hot spot in science which has taken the efforts of researchers around the world. Recently a review of the works done in bio-mimetic compounds was published by Schilter et al.. [22] Showing that some studies have got promising results in bio-mimetic compounds synthesized in laboratory.

Molecular modeling of bio-mimetic compounds of hydrogenases assisted with software

Recently the possibility of study such compounds using molecular modeling assisted by informatic software has opened new possibilities in the study of the redox reaction of biomimetic compounds. For example, using "Density Functional Theory" (DFT) computer modeling made it possible to propose a catalytic pathway of H2 binding on the catalytic center of hydrogenase (Greco [23] ). Other example of the application of computational modeling in the study of hydrogenases is the work done by Breglia et al., [24] whose results shows the chemical pathway of how oxygen inhibited the redox reaction of [NiFe] hydrogenases.

Bio-mimetic compounds inspired in [Fe] hydrogenases

The Fe-only hydrogenases are particularly common enzymes for synthetic organometallic chemists to mimic. This interest is motivated by the inclusion of high field ligands like cyano and CO (metal carbonyl) in the first coordination sphere of the pertinent di-iron cluster. Free cyano and carbonyl ligands are toxic to many biological systems. So, their inclusion in this system suggests they play pivotal roles. These high field ligands may ensure the iron centers at the active site remain in a low spin state throughout the catalytic cycle. In addition, there is bridging dithiolate between the two iron centers. This dithiolate has a three atom backbone in which the identity of the central atom is still undetermined; it models crystallographically as a CH2, NH or O group. There is reason to believe that this central atom is an amine which functions as a Lewis base. This amine combined with Lewis acidic iron centers makes the enzyme a bifunctional catalyst which can split hydrogen between a proton acceptor and a hydride acceptor or produce hydrogen from a proton and hydride.

Since none of the ligands on the iron centers are part of the enzyme's amino acid backbone, they can not be investigated through site-directed mutagenesis, but enzyme mimicry is a feasible approach.

Breadth

Many elegant structural mimics have been synthesized reproducing the atomic content and connectivity of the active site. [25] The work by Pickett is a prime example of this field. [26] The catalytic activity of these mimics do not however compare to the native enzyme. In contrast, functional mimics, also known as bio-inspired catalysts, aim to reproduce only the functional features of an enzyme often through the use of different atomic content and connectivity from that found in the native enzymes. Functional mimics have made advances in the reactive chemistry and have implications on the mechanistic activity of the enzyme as well as acting as catalysts in their own right. [27] [28] [29]

Related Research Articles

<span class="mw-page-title-main">Inorganic chemistry</span> Field of chemistry

Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, as there is much overlap in the subdiscipline of organometallic chemistry. It has applications in every aspect of the chemical industry, including catalysis, materials science, pigments, surfactants, coatings, medications, fuels, and agriculture.

<span class="mw-page-title-main">Organometallic chemistry</span> Study of organic compounds containing metal(s)

Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide, cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term "metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are representative members of this class. The field of organometallic chemistry combines aspects of traditional inorganic and organic chemistry.

Ferrocene is an organometallic compound with the formula Fe(C5H5)2. The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, and is soluble in most organic solvents. It is remarkable for its stability: it is unaffected by air, water, strong bases, and can be heated to 400 °C without decomposition. In oxidizing conditions it can reversibly react with strong acids to form the ferrocenium cation Fe(C5H5)+2. Ferrocene and the ferrocenium cation are sometimes abbreviated as Fc and Fc+ respectively.

Iron–sulfur proteins are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q – cytochrome c reductase, succinate – coenzyme Q reductase and nitrogenase. Iron–sulfur clusters are best known for their role in the oxidation-reduction reactions of electron transport in mitochondria and chloroplasts. Both Complex I and Complex II of oxidative phosphorylation have multiple Fe–S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally, some Fe–S proteins regulate gene expression. Fe–S proteins are vulnerable to attack by biogenic nitric oxide, forming dinitrosyl iron complexes. In most Fe–S proteins, the terminal ligands on Fe are thiolate, but exceptions exist.

A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen (H2), as shown below:

<span class="mw-page-title-main">Sandwich compound</span> Chemical compound made of two ring ligands bound to a metal

In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic, covalent bonds to two arene (ring) ligands. The arenes have the formula CnHn, substituted derivatives and heterocyclic derivatives. Because the metal is usually situated between the two rings, it is said to be "sandwiched". A special class of sandwich complexes are the metallocenes.

Bioorganometallic chemistry is the study of biologically active molecules that contain carbon directly bonded to metals or metalloids. The importance of main-group and transition-metal centers has long been recognized as important to the function of enzymes and other biomolecules. However, only a small subset of naturally-occurring metal complexes and synthetically prepared pharmaceuticals are organometallic; that is, they feature a direct covalent bond between the metal(loid) and a carbon atom. The first, and for a long time, the only examples of naturally occurring bioorganometallic compounds were the cobalamin cofactors (vitamin B12) in its various forms. In the 21st century, as a result of the discovery of new systems containing carbon–metal bonds in biology, bioorganometallic chemistry is rapidly emerging as a distinct subdiscipline of bioinorganic chemistry that straddles organometallic chemistry and biochemistry. Naturally occurring bioorganometallics include enzymes and sensor proteins. Also within this realm are synthetically prepared organometallic compounds that serve as new drugs and imaging agents (technetium-99m sestamibi) as well as the principles relevant to the toxicology of organometallic compounds (e.g., methylmercury). Consequently, bioorganometallic chemistry is increasingly relevant to medicine and pharmacology.

<span class="mw-page-title-main">Formate dehydrogenase</span>

Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to carbon dioxide, donating the electrons to a second substrate, such as NAD+ in formate:NAD+ oxidoreductase (EC 1.17.1.9) or to a cytochrome in formate:ferricytochrome-b1 oxidoreductase (EC 1.2.2.1). This family of enzymes has attracted attention as inspiration or guidance on methods for the carbon dioxide fixation, relevant to global warming.

<span class="mw-page-title-main">Ferredoxin hydrogenase</span> Class of enzymes

In enzymology, ferredoxin hydrogenase, also referred to as [Fe-Fe]hydrogenase, H2 oxidizing hydrogenase, H2 producing hydrogenase, bidirectional hydrogenase, hydrogenase (ferredoxin), hydrogenlyase, and uptake hydrogenase, is found in Clostridium pasteurianum, Clostridium acetobutylicum,Chlamydomonas reinhardtii, and other organisms. The systematic name of this enzyme is hydrogen:ferredoxin oxidoreductase

Transition metal hydrides are chemical compounds containing a transition metal bonded to hydrogen. Most transition metals form hydride complexes and some are significant in various catalytic and synthetic reactions. The term "hydride" is used loosely: some of them are acidic (e.g., H2Fe(CO)4), whereas some others are hydridic, having H-like character (e.g., ZnH2).

An enzymatic biofuel cell is a specific type of fuel cell that uses enzymes as a catalyst to oxidize its fuel, rather than precious metals. Enzymatic biofuel cells, while currently confined to research facilities, are widely prized for the promise they hold in terms of their relatively inexpensive components and fuels, as well as a potential power source for bionic implants.

Enzyme mimic is a branch of biomimetic chemistry, which aims at imitating the function of natural enzymes. An enzyme mimic is a small molecule complex that models the molecular structure, spectroscopic properties, or reactivity of an enzyme, sometimes called bioinspired complexes.

<span class="mw-page-title-main">Iron–nickel clusters</span>

Iron–nickel (Fe–Ni) clusters are metal clusters consisting of iron and nickel, i.e. Fe–Ni structures displaying polyhedral frameworks held together by two or more metal–metal bonds per metal atom, where the metal atoms are located at the vertices of closed, triangulated polyhedra.

<span class="mw-page-title-main">Rhodocene</span> Organometallic chemical compound

Rhodocene is a chemical compound with the formula [Rh(C5H5)2]. Each molecule contains an atom of rhodium bound between two planar aromatic systems of five carbon atoms known as cyclopentadienyl rings in a sandwich arrangement. It is an organometallic compound as it has (haptic) covalent rhodium–carbon bonds. The [Rh(C5H5)2] radical is found above 150 °C (302 °F) or when trapped by cooling to liquid nitrogen temperatures (−196 °C [−321 °F]). At room temperature, pairs of these radicals join via their cyclopentadienyl rings to form a dimer, a yellow solid.

Marcetta York Darensbourg is an American inorganic chemist. She is a Distinguished Professor of Chemistry at Texas A&M University. Her current work focuses on iron hydrogenases and iron nitrosyl complexes.

<span class="mw-page-title-main">Iron hydride</span> Index of articles associated with the same name

An iron hydride is a chemical system which contains iron and hydrogen in some associated form.

[NiFe] hydrogenase is a type of hydrogenase, which is an oxidative enzyme that reversibly converts molecular hydrogen in prokaryotes including Bacteria and Archaea. The catalytic site on the enzyme provides simple hydrogen-metabolizing microorganisms a redox mechanism by which to store and utilize energy via the reaction

An azadithiolate cofactor is an anion with the formula NH(CH2S)22−. It is used as a cofactor in the [FeFe] hydrogenases, bacterial enzymes responsible for the reversible reduction of 2 H+ to H2. As a cofactor, the two thiolate functional groups are bound to each of the two irons in the active site of the enzyme in a bridging fashion. The amine functional group serves as an acid/base to transfer H+ from the solution to the active site. The proton transfer function of this cofactor is of great importance to the activity of the hydrogenase enzyme, as H2 evolution will not occur if the amine is not present.

<span class="mw-page-title-main">Diiron propanedithiolate hexacarbonyl</span> Chemical compound

Diiron propanedithiolate hexacarbonyl is the organoiron complex with the formula Fe2(S2C3H6)(CO)6. It is a red diamagnetic solid. It adopts a symmetrical structure with six terminal CO ligands. The complex is a precursor to hydrogenase mimics.

<span class="mw-page-title-main">Wolfgang Lubitz</span> German chemist and biophysicist

Wolfgang Lubitz is a German chemist and biophysicist. He is currently a director emeritus at the Max Planck Institute for Chemical Energy Conversion. He is well known for his work on bacterial photosynthetic reaction centres, hydrogenase enzymes, and the oxygen-evolving complex using a variety of biophysical techniques. He has been recognized by a Festschrift for his contributions to electron paramagnetic resonance (EPR) and its applications to chemical and biological systems.

References

  1. Selvaggi, A; Barberini, U; Franchi, E; Rodriguez, F; Pedroni, P (1999). "In vitro hydrogen photoproduction using Pyrococcus furiosus sulfhydrogenase and TiO2". Journal of Photochemistry and Photobiology. 125 (1–3): 107–112. doi:10.1016/S1010-6030(99)00088-X.
  2. Hallenbeck, P; Benemann, J (2002). "Biological hydrogen production; fundamentals and limiting processes". Hydrogen Energy: 1185–1193.
  3. Collman, J; Wagenknecht, P; Lewis, N (1992). "Hydride transfer and dihydrogen elimination from osmium and ruthenium metalloporphyrin hydrides: model processes for hydrogenase enzymes and the hydrogen electrode reaction". Journal of the American Chemical Society. 14 (114): 5665–5674.
  4. Artero, V; Fontecave, S (2005). "Some general principles for designing electrocatalysts with hydrogenase activity". Coordination Chemistry Reviews. 249 (15–16): 1518–1535. doi:10.1016/j.ccr.2005.01.014.
  5. Manor, B; Rauchfuss, T (2013). "Hydrogen Activation by Biomimetic [NiFe]-Hydrogenase Model Containing Protected Cyanide Cofactors". Journal of the American Chemical Society. 135 (32): 11895–11900. doi:10.1021/ja404580r. PMC   3843950 . PMID   23899049.
  6. Kluwer, A; Kaprea, F; Hartla, M; Lutzb, A; Spekb, A; Brouwera, P; Van Leeuwena, L; Reek, J (2008). "Self-assembled biomimetic [2Fe2S]-hydrogenasebased photocatalyst for molecular hydrogen evolution". Proceedings of the National Academy of Sciences of the United States of America. 26: 10460–10465.
  7. Sun, L; Ott, S; Kritikos, M; Akermark, B; Lomoth, R (2004). "A Novel Biomimetic Catalyst for Electrochemical Hydrogen Production". Preprints of Papers- American Chemical Society, Division of Fuel Chemistry. 1: 109–111.
  8. Zhao, J; Ma, Y; Bai, Z; Chang, W; Li, J (2012). "A new reactivity pattern of heterodinuclear complexes [MnRe(CO)6(m-S2CPR3)] with nBuLi/protonation and its electrochemistry properties investigation as structure and function models for the Fe only hydrogenase active site". Journal of Organometallic Chemistry. 716: 230–236. doi:10.1016/j.jorganchem.2012.07.003.
  9. Liu, X; Ru, X; Li, Y; Zhang, K; Chen, D (2011). "A polyene-based polymer functionalized with a model of [FeFe]-hydrogenase and film electrodes assembled from the polymer via spin-coating". International Journal of Hydrogen Energy. 36 (16): 9612–9619. doi:10.1016/j.ijhydene.2011.05.095.
  10. Na, Y; Wang, M; Jin, K; Zhang, R; Sun, L (2006). "An approach to water-soluble hydrogenase active site models: Synthesis and electrochemistry of diiron dithiolate complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1] nonane ligand(s)". Journal of Organometallic Chemistry. 691 (23): 5045–5051. doi:10.1016/j.jorganchem.2006.08.082.
  11. Morozov, S; Vignais, P; Cournac, L; Zorin, N; Karyakina, A; Cosnier, S (2002). "Bioelectrocatalytic hydrogen production by hydrogenase electrodes". International Journal of Hydrogen Energy. 27 (11–12): 1501–1505. doi:10.1016/S0360-3199(02)00091-5.
  12. Oh, Y; Lee, Y; Choi, E; Kim, M (2008). "Bioelectrocatalytic hydrogen production using Thiocapsa roseopersicina hydrogenase in two-compartment fuel cells". International Journal of Hydrogen Energy. 33 (19): 5218–5223. doi:10.1016/j.ijhydene.2008.05.015.
  13. Varpness, Z; Peters, J; Young, M; Douglas, T (2005). "Biomimetic Synthesis of a H2 Catalyst Using a Protein Cage Architecture". Nano Letters. 11: 2306–2309.
  14. Johnston, W; Cooney, M; Liaw, B; Sapra, R; Adams, M (2005). "Design and characterization of redox enzyme electrodes: new perspectives on established techniques with application to an extremeophilic hydrogenase". Enzyme and Microbial Technology. 36 (4): 540–549. doi:10.1016/j.enzmictec.2004.11.016.
  15. Constable, C; Housecroft, C; Kokatam, S; Medlycott, A; Zampese, J (2010). "Fe-only hydrogenase active site mimics: Fe2(CO)6(l-ADT) (ADT = azadithiolate) clusters bearing pendant 2,20:60,200-terpyridine domains and containing alkynylthienylene or alkynylphenylene spacers". Inorganic Chemistry Communications. 13: 457–460. doi:10.1016/j.inoche.2009.06.003.
  16. Apfel, U; Kowol, C; Kloss, F; Gorls, H; Keppler, B; Weigand, W (2011). "Hydroxy and ether functionalized dithiolanes: Models for the active site of the [FeFe] hydrogenase". Journal of Organometallic Chemistry. 696 (5): 1084–1088. doi:10.1016/j.jorganchem.2010.09.048.
  17. Goff, A; Artero, V; Metaye, R; Moggia, F; Jousselme, B; Razavet, M; Tran, P; Palacin, S; Fontecave, M (2010). "Immobilization of FeFe hydrogenase mimics onto carbon and gold electrodes by controlled aryldiazonium salt reduction: An electrochemical, XPS and ATR-IR study". International Journal of Hydrogen Energy. 35 (19): 10790–10796. doi:10.1016/j.ijhydene.2010.02.112.
  18. Donovan, E; Nichol, G; Felton, G (2013). "Structural effects upon the durability of hydrogenase-inspired hydrogen-producing electrocatalysts: Variations in the (m-edt) [Fe2(CO)6] system". Journal of Organometallic Chemistry. 726: 9–13. doi:10.1016/j.jorganchem.2012.12.006.
  19. Martin, M; Vidotti, M; Souza, F (2012). "Synthesis, characterization and electrocatalysis of mono- and di-nickel tetraiminodiphenolate macrocyclic complexes as active site models of [NiFe]-hydrogenases". International Journal of Hydrogen Energy. 37 (19): 14094–14102. doi:10.1016/j.ijhydene.2012.06.118.
  20. Hogarth, G; Richards, I (2006). "Synthesis, crystal structure and protonation of the asymmetric iron-only hydrogenase model [Fe2(CO)3(l-pdt){l,g2-Ph2PCH2CH2P(Ph) CH2CH2PPh2}] (pdt = SCH2CH2CH2S)". Inorganic Chemistry Communications. 10: 66–70. doi:10.1016/j.inoche.2006.09.005.
  21. Zhang, Y; Hu, M; Wen, H; Si, T; Ma, C; Chen, C; Liu, Q (2009). "Terminal pyridine-N ligation at [FeFe] hydrogenase active-site mimic". Journal of Organometallic Chemistry. 694 (16): 2576–2580. doi:10.1016/j.jorganchem.2009.03.050.
  22. Schilter, D; Camara, J; Huynh, M; Hammes-Schiffer, S; Rauchfuss, T (2016). "Hydrogenase Enzymes and Their Synthetic Models: The Role of Metal Hydrides". Chemical Reviews. 116 (15): 8693–8749. doi:10.1021/acs.chemrev.6b00180. PMC   5026416 . PMID   27353631.
  23. Geco, C (2013). "H2 Binding and Splitting on a New-Generation [FeFe]-Hydrogenase Model Featuring a Redox-Active Decamethylferrocenyl Phosphine Ligand: A Theoretical Investigation". Inorganic Chemistry. 52 (4): 1901–1908. doi:10.1021/ic302118h. PMID   23374093.
  24. Breglia, R; Ruiz‑Rodriguez, M; Vitriolo, A; Gonzàlez‑Laredo, R; De Gioia, L; Greco, C; Bruschi, M (2017). "Theoretical insights into [NiFe]‑hydrogenases oxidation resulting in a slowly reactivating inactive state". Journal of Biological Inorganic Chemistry. 22 (1): 137–151. doi:10.1007/s00775-016-1416-1. PMID   27873068.
  25. L Schwartz, G Eilers, L Eriksson, A Gogoll, R Lomoth and S Ott, Chem. Commun., 2006 doi : 10.1039/b514280f
  26. Cédric Tard, Xiaoming Liu, Saad K. Ibrahim, Maurizio Bruschi, Luca De Gioia, Siân C. Davies, Xin Yang, Lai-Sheng Wang, Gary Sawers and Christopher J. Pickett Nature (10 Feb 2005) 433, 610 - 613.
  27. Wilson, A. D.; Newell, R. H.; McNevin, M. J.; Muckerman, J. T.; Rakowski DuBois, M.; DuBois, D. L. J. Am. Chem. Soc.2006128(1) 358-366.
  28. Hu, Xile; Cossairt, Brandi M.; Brunschwig, Bruce S.; Lewis, Nathan S.; Peters, Jonas C. Chem. Commun., 200537, 4723-4725.
  29. Baffert, Carole; Artero, Vincent; Fontecave, Marc. Inorganic Chemistry200746(5), 1817-1824.