Iron hydrogenase and

Horner DS, Foster PG, Embley TM (2000) Iron hydrogenases and the evolution of anaerobic eukaryotes. Mol Biol Evol 17 1695-1709... 

Hausmann A, Aguilar Netz DJ, Balk J, Pierik AJ, Muhlenhoff U, Lill R (2005) The eukaryotic P loop NTPase NBP35 An essential component of the cytosolic and nuclear iron-sulfur protein assembly machinery. Proc Natl Acad Sci USA 102 3266-3271 Henriquez FL, Richards , Roberts F, McLeod R, Roberts CW (2005) The unusual mitochondrial compartment of Cryptosporidium parvum. Trends Parasitol 21 68-74 Horner DS, Foster PG, Embley TM (2000) Iron hydrogenases and the evolution of anaerobic eukaryotes. Mol Biol Evol 17 1695-1709... 

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... 

NICKEL-IRON-SULFUR ACTIVE SITES HYDROGENASE AND CO DEHYDROGENASE... 

Hydrogenase and other components of the N2 fixing apparatus of bacteria have been shown to be non-heme iron proteins (66). 

Nickel-Iron-Sulfur Active Sites Hydrogenase and CO Dehydrogenase Juan C. Fontecilla-Camps and Stephen W. Ragsdale... 

Twenty years ago, the first spectroscopic studies were initiated on hydrogenases, and Mossbauer was first applied in 1982 to characterize the iron clusters present in D. desulfuricans hydrogenase (Kruger et al. 1982). Different enzymes have been studied since through a spectroscopic approach. In the remainder of this section, we will present as an example of these studies the work done in the D. gigas [NiFe] hydrogenase (Huynh et al. 1987 Teixeira et al. 1989). 

Figure 10.3 Z-scheme of oxygenic photosynthesis in green algae and cyanobacteria, showing links to hydrogenase. Q (plastoquinone) and X (an iron-sulfur cluster) are electron acceptors from photosystems II and I, respectively.The two hydrogenases shown are the NADP-dependent bidirectional hydrogenase and a ferredoxin-dependent enzyme.

Amara, P. V., Volbeda, A., Fontecilla-Camps, J. C. and Field, M. J. A. (1999) Hybrid density functional theory/molecular mechanics study of nickel-iron hydrogenase Investigation of the active site redox states./. Am. Chem. Soc., 121, 4468-77. 

Butt, J. N., Filipiak, M. and Hagen, W. R. (1997) Direct electrochemistry oi Megasphaera elsdenii iron hydrogenase. Definition of the enzymes catalytic operating potential and quantitation of the catalytic behaviour over a continuous potential range. Eur. J. Biochem., 245,116-22. 

Nicolet, Y., Piras, C., Legrand, P., Hatchikian, C. E. and Fontecilla-Camps, J. C. (1999) Desulfovibrio desulfuricans iron hydrogenase The structure shows unusual coordination to an active site Fe binuclear center. Structure Fold. Des., 7, 13-23. 

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. 

Verhagen, M. F., ORourke, T. and Adams, M. W. (1999) The hyperthermophilic bacterium, Thermotoga maritime, contains an unusually complex iron-hydrogenase Amino acid sequence analyses versus biochemical characterization. Biochim. Biophys. Acta, 1412, 212-29. 

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. 

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). 

It is important to point out that D. vulgaris hydrogenase contains three multinuclear iron clusters and each cluster may exist in equilibrium between two different oxidation states in each sample. Consequently, the raw Mossbauer spectra are complex, consisting of overlapping spectra originating from different iron sites of these various clusters. For clarity, we present only the deconvoluted spectra of the H cluster. These spectra were prepared by removing the contributions of other iron species from the raw spectra. Details of the analysis are available (Pereira et al. 2001). 

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