Nickel-iron hydrogenases

Frenking G, Cremer D (1990) The Chemistry of the Nobles Gas Elements Helium, Neon, and Argon - Experimental Facts and Theoretical Predictions. 73 17-96 Frey M (1998) Nickel-Iron Hydrogenases Structural and Functional Properties. 90 97-126 Fricke B (1975) Superheavy Elements. 21 89-144... 

De Luca G, P de Philip, Z Dermoun, M Rouseet, A Vermeglio (2001) Reduction of Technetium (VII) by Desulfovibrio fructosovorans is mediated by the nickel-iron hydrogenase. Appl Environ Microbiol 67 468-475. 

Amara, P., Volbeda, A., Fontecilla-Camps, J. C., Field, M. J., 1999, A Hybrid Density Functional Theory/Mo-lecular Mechanics Study of Nickel-Iron Hydrogenase Investigation of the Active Site Redox States , J. Am. Chem. Soc., 121, 4468. 

Sorgenfrei, O., Linder, D., Karas, M. and Klein, A. (1993a) A novel very small subunit of a selenium containing [nickel-iron] hydrogenase of Methanococcus voltae is postranslation-ally processed by cleavage at a defined position. Eur. J. Biochem., 213, 1355-8. 

Volbeda, A., Charon, M.-H., Piras, C., Hatchikian, E. C., Frey, M. and Fontecilla-Camps, J. C. (1995) Crystal structure of the nickel-iron hydrogenase from Desulfovibrio gigas. Nature (London), 373, 580-7. 

Frey M. 1998. Nickel-iron hydrogenases structural and functional properties. Struct Bonding 90 98-126. 

Volbeda A, Charon M-H, Piras C, et al. 1995. Crystal structure of the nickel-iron hydrogenase from Desulfovibrio gigas. Nature 373 580-7. 

Each iron atom is terminally coordinated by one CO and one CN . The coordination of Fel is completed by the additional bridging cysteinyl sulfur. For Fe2, the sixth coordination site may be empty, as in the D. desulfuricans enzyme (Nicolet et al. 1999), or occupied by a solvent molecule, as observed in the C. pasteurianum enzyme (Peters et al. 1999). The assignment for the diatomic ligands is supported by infrared spectroscopic evidence (Pierik et al. 1998X and similar diatomic ligands have also been found for the corresponding binuclear [Ni-Fe] cluster of the nickel-iron hydrogenases (Volbeda et al. 1995). 

Figure 18.4. Proposed biocorrosion model for cathodic electron depolarization of mild steel by D. vulgaris Hildenborough. CM, cytoplasmic membrane HMC, high molecular weight cytochrome [Fe] Fl2ase, iron hydrogenase [NiFe] H2ase, nickel iron hydrogenase ETS, electron transport system.

Nickel-iron hydrogenases [NiFe] (Figure 8.2) are present in several bacteria. Their structure is known [22, 23] to be a heterodimeric protein formed by four subunits, three of which are small [Fe] and one contains the bimetallic active center consisting of a dimeric cluster formed by a six coordinated Fe linked to a pentacoordinated Ni (III) through two cysteine-S and a third ligand whose nature changes with the oxidation state of the metals in the reduced state it is a hydride, H, whereas in the oxidized state it may be either an oxo, 0, or a sulfide,... 

Pavlov M, Siegbahn PEM, Blomberg MRA, Crabtree RH (1998) Mechanism of H-H activation by nickel-iron hydrogenase. J. Am. Chem. Soc. 120 548-555... 

Pavlov M, Blomberg MRA, Siegbahn PEM (1999) New aspects of H2 activation by nickel-iron hydrogenase, Int. J. Quant. Chem. 73 197-207... 

Niu S (1999) Thomson LM, Hall MB, Theoretical characterization of the reaction intermediates in a model of the nickel-iron hydrogenase of Desulfovibrio gigas. J. Am. Chem. Soc. 121 4000-4007... 

Amara P, Volbeda A, Fontecilla-Camps JC, Field MJ (1999) A hybrid density functional theory/molecular mechanics study of nickel-iron hydrogenase investigation of the active site redox states J. Am. Chem. Soc. 121 4468—1477... 

Stadler C, de Lacey AL, Hernandez B, Fernandez VM, Conesa JC (2002) Density functional calculations for modeling the oxidized states of the active site of nickel-iron hydrogenases. 1. Verification of the method with paramagnetic Ni and Co complexes. Inorg. Chem. 41 4417 1423... 

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