Hydrogenases NiFeSe

The hydrogenases, [NiFe] hydrogenase, [NiFeSe] hydrogenase and [Fe] hydrogenase, have been studied. [NiFe] hydrogenase has Ni and Fe atoms at its active site, which play a central role in the catalytic reaction. It is found in anaerobic... 

Nickel-selenium coordination compounds have received attention in recent years, because a unique Ni-selenocysteine interaction was revealed in the active site of [FeNiSe]-hydrogenases.1083,1084 Of particular interest in this regard are mixed CO/selenolate complexes. Distorted square planar (393) was prepared from [CpNi(CO)]2, PhSeSePh, and [Fe(CO)3(SePh)3] and provides the first example of CO bound to a square planar Ni11 center in thiolate/selenolate environment.1085,1086 Upon addition of RSSR, species of the series [Ni(CO)(SR) (SePh)3 ] are formed. //(CO) ranges from 2,023 cm-1 to 2,043 cm-1 and is regarded as a spectroscopic reference for the CO binding site in [NiFeSe] hydrogenases. 

The catalytic site of [NiFe] and [NiFeSe] hydrogenases in oxidised inactive and reduced active states... 

Figure 6.10 The catalytic site of [NiFe] and [NiFeSe] hydrogenases in oxidised inactive (top) and reduced active (bottom) states. Note the three non-protein diatomic ligands to the iron.The site bridging the Ni and Fe is occupied by an oxygen or sulfur species in the most oxidised states and probably by a hydride or molecular hydrogen in the most reduced states.

De Gioia, L., Fantucci, P., Guigliarelli, B. and Bertrand, P. (1999b) Ah initio invstigation of the structural and electronic differences between active site models of [NiFe] and [NiFeSe] hydrogenases. Int.]. Quant. Chem., 73, 187-95. 

Garcin, E., Vemede, X., Hatchikian, E. C., Volbeda, A., Frey, M. and Fontecilla-Camps, J. C. (1999) The crystal structure of a reduced [NiFeSe] hydrogenase provides an image of the activated catal) tic center. Structure Fold. Des., 7, 557-66. 

He, S. H., Teixeira, M., LeGall, J., Patil, D. S., Moura, L, Moura, J. J., DerVartanian, D. V., Huynh, B. H. and Peck, H. D. Jr (1989b) EPR studies with 02-enriched (NiFeSe) hydrogenase of Desulfovibrio baculatus. Evidence for a selenium ligand to the active site nickel. J. Biol. Chem., 264, 2678-82. 

Stein M, Lubitz W (2001) The electronic structure of the catalytic intermediate Ni-C in [NiFe] and [NiFeSe] hydrogenases. Phys. Chem. Chem. Phys. 3 5115-5120... 

Wang C-P, Franco R, Moura JJG, Moura I, Day EP (1992) The nickel site in active Desulfovibrio baculatus [NiFeSe] hydrogenase is diamagnetic. Multifield saturation magnetization measurement of the spin state of Ni(II). J. Biol. Chem. 267 7378—7380... 

Several crystal structures of [NiFe] hydrogenases have been determined from sulfate-reducing and photosynthetic bacteria [8, 84, 85], and recently also from oxygen-tolerant species [9, 10]. Two structures from the subclass [NiFeSe] hydrogenase are known [86-88] and from two [FeFe] hydrogenases [8, 89, 90],... 

Marques MC, Coelho R, de Lacey AL, Pereira IAC, Matias PM. The three-dimensional structure of [NiFeSe] hydrogenase from Desulfovibrio vulgaris Hildenborough a hydrogenase without a bridging ligand in the active site in its oxidised, as-isolated state. J Mol Biol. 2010 396(4) 893—907. 

Marjory Stephenson and Leonard Stickland named the enzyme in 1931 (Stephenson and Stickland, 1931). There are five types of hydrogenase. Three of these are Ni proteins and one contains iron as the only transition metal. These proteins catalyze the reversible oxidation of dihydrogen gas (Eq. 7). A fifth class of hydrogenase lacks metals and catalyzes Eq. 8, but not Eq. 7. The Ni enzymes are classed into the NiFe, the NiFeSe, and the hydrogen sensors. All of these enzymes are bidirectional, although different enzymes exhibit a catalytic bias toward making or oxidizing H2. 

---