Nickel–Iron–Selenium Hydrogenases – An Overview

Abstract

[NiFeSe] hydrogenases are a sub-group of the large family of [NiFe] hydrogenases in which a selenocysteine ligand is coordinating the Ni at the active site. As observed for other selenoproteins, the [NiFeSe] hydrogenases display much higher catalytic activities than their Cys-containing homologues. Here we review the biochemical, catalytic, spectroscopic and structural properties of known [NiFeSe] hydrogenases, namely from the Hys, Fru and Vhu families. A survey of new [NiFeSe] hydrogenases present in the databases showed that all enzymes belong to either group 1 periplasmic uptake hydrogenases (Hys) or to group 3 cytoplasmic hydrogenases (Fru and Vhu), and are present in either sulfate-reducing or methanogenic microorganisms. In both kinds of organisms the [NiFeSe] hydrogenases are preferred over their Cyscontaining homologues if selenium is available. Since no structural information is available for the Vhu and Fru enzymes, we have modelled the large subunit of these enzymes and analyzed the area surrounding the active site. Three [NiFeSe] hydrogenases of the Hys and Vhu types were identified in which the selenocysteine residue is found in a different location in the sequence, which should result in a surprising coordination to the Ni as a bridging, rather than terminal, ligand. The high activity and fast reactivation, together with a degree of oxygen tolerance for the H 2 -production activity, make the Hys hydrogenases attractive catalysts for technological applications. ____________ [a]Protein Modeling

Nickel-based cocatalysts for photocatalytic hydrogen production

“…According to the metal ion composition of the active sites, H 2 ases can be classified into three phylogenetically distinct groups, namely [NiFe], [FeFe] and [Fe] H 2 ases [132,133]. Among them, [NiFe]-H 2 ases are the most abundant group of H 2 ases and show excellent H 2 evolution activity and good H 2 -and O 2 -tolerance [134]. They allow for the accumulation of H 2 during irradiation and can effectively function even in aerobic conditions.…”

Spectroscopic and Electrochemical Characterization of the [NiFeSe] Hydrogenase from Desulfovibrio vulgaris Miyazaki F: Reversible Redox Behavior and Interactions between Electron Transfer Centers

“…[3e] The oxygen tolerance exhibited by the membrane- [9,10] These selenium-containing hydrogenases have been found in a number of species, including the sulfate-reducing bacteria Desulfovibrio baculatum (Db) and Desulfovibrio vulgaris Hildenborough (DvH), and methanogenic archaebacteria like Methanococcus voltae. Studies with FTIR and EPR spectroscopy have been carried out to characterize these enzymes.…”

Structural features of [NiFeSe] and [NiFe] hydrogenases determining their different properties: a computational approach

“…Illustrative of their capacity to be used in biotechnological applications is the fact that the [NiFeSe] hydrogenase from Desulfomicrobium baculatum has shown the best performance in experimental H 2 -producing devices among several other hydrogenases [11,12]. In [NiFeSe] hydrogenases one of the cysteine residues coordinating the nickel ion at the active site in standard [NiFe] hydrogenases is replaced by a selenocysteine [7,9,[13][14][15] (Fig. 1).…”

“…Among the [NiFe] class, there is a subgroup of enzymes, designated as [NiFeSe] hydrogenases, with especial catalytic properties which make them particularly suited for technological applications [7]. The [NiFeSe] hydrogenases are able to catalyze H 2 production in the presence of O 2 , and so they are considered oxygen-tolerant [8][9][10].…”