ISSN:
1432-1327
Keywords:
Key words Hydrogenase
;
Nickel
;
Iron-sulfur
;
Hyperthermophilic organisms
;
Electron paramagnetic resonance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The sulfhydrogenase complex of Pyrococcus furiosus is an αβγδ heterotetramer with both hydrogenase activity (borne by the αδ subunits) and sulfur reductase activity (carried by the βγ subunits). The β-subunit contains at least two [4Fe-4S] cubanes and the γ-subunit contains one [2Fe-2S] cluster and one FAD molecule. The δ-subunit contains three [4Fe-4S] cubanes and the α-subunit carries the NiFe dinuclear center. Only three Fe/S signals are observed in EPR-monitored reduction by dithionite, NADPH, or internal substrate upon heating. All other clusters presumably have reduction potentials well below that of the H+/H2 couple. Heat-induced reduction by internal substrate allows, for the first time, EPR monitoring of the NiFe center in a hyperthermophilic hydrogenase, which passes through a number of states, some of which are similar to states previously defined for mesophilic hydrogenases. The complexity of the observed transitions reflects a combination of temperature-dependent activation and temperature-dependent reduction potentials.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050314
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