The iron-sulphur centres of soluble hydrogenase from Alcaligenes eutrophus

Nickel hydrogenases: in search of the active site

“…The soluble enzyme from the Knallgas bacterium A. eutrophus H-16, which contains FMN in addition to Fe and nickel, catalyzes the reduction of NAD + by H 2. This reaction is not affected by CO or 0 2 [174]. The oxidized enzyme cannot react with Hz, however, unless a catalytic amount of NADH is added.…”

“…One example is the F420-reducing hydrogenase from M. thermoautotrophicum [76,106,132], where hydrogenase is associated with a flavo-iron-sulphur enzyme able to reduced 8-hydroxy-5-deazaflavin (factor F420). A second example is the soluble NAD+-reducing hydrogenase from A. eutrophus and Nocardia opaca [174,177,229]. These enzymes are in fact H2:NAD + oxidoreductases composed of two enzyme units: a nickel hydrogenase and an NADH dehydrogenase.…”

Reversible hydrogenase of Anabaena variabilis ATCC 29413: catalytic properties and characterization of redox centres

“…eutrophus. The latter enzyme contains nickel and FMN, and has a high content of iron and sulphide, including at least one [2Fe-2S] cluster [18,29].…”

Electron paramagnetic resonance and other properties of hydrogenases isolated from Desulfovibrio vulgaris (strain Hildenborough) and Megasphaera elsdenii

“…It is, therefore, acceptable to assume that both enzymes contain three of the 4Fe-4S type of clusters, although a report of a hydrogenase with 2Fe-2S clusters has been published [25]. Cluster extrusion, if successful, is a technique which is highly indicative of the kind and number of clusters present.…”

“…To date, there is no published evidence from cluster displacement (core extrusion) studies for the presence of anything but tetranuclear Fe-S centers in any hydrogenase. Recently, however, solventperturbed EPR studies on the unusual FMN-containing soluble hydrogenase of Alcaligenes eutrophus led to the conclusion that there were two 2Fe-2S and two 4Fe-4S centers per molecule [25]. Apparently tetranuclear iron-sulfur centers are necessary cofactors for the hydrogenase reaction.…”