Spectroscopic characterization of the key catalytic intermediate Ni-C in the O2-tolerant [NiFe] hydrogenase I from Aquifex aeolicus: evidence of a weakly bound hydride.
نویسندگان
چکیده
Ni-C in the O(2)-tolerant hydrogenase I from Aquifex aeolicus binds a hydride weaker than that in O(2)-sensitive hydrogenases. This is in line with the enhanced light-sensitivity of Ni-C, greater lability of the hydride complex and increased catalytic redox potentials relevant to bio-H(2) oxidation.
منابع مشابه
Hydrogen metabolism in the hyperthermophilic bacterium Aquifex aeolicus.
Aquifex aeolicus is a microaerophilic, hydrogen-oxidizing, hyperthermophilic bacterium containing three [NiFe] hydrogenases. Two of these three enzymes (one membrane-bound and one soluble) have been purified and characterized. The Aquifex hydrogenases are thermostable and tolerant to oxygen. A cellular function for the three hydrogenases has been proposed. The two membrane-bound periplasmic hyd...
متن کاملLight-induced reactivation of O2-tolerant membrane-bound [Ni-Fe] hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus under turnover conditions.
We report the effect of UV-Vis light on the membrane-bound [Ni-Fe] hydrogenase from Aquifex aeolicus under turnover conditions. Using electrochemistry, we show a potential dependent light sensitivity and propose that a light-induced structural change of the [Ni-Fe] active site is related to an enhanced reactivation of the hydrogenase under illumination at high potentials.
متن کاملDiscovery of Dark pH-Dependent H+ Migration in a [NiFe]-Hydrogenase and Its Mechanistic Relevance: Mobilizing the Hydrido Ligand of the Ni-C Intermediate
Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H2 so efficiently remains unclear. A well-known EPR-active state produced under H2 and known as Ni-C is assigned as a Ni(III)-Fe(II) species with a hydrido ligand in the bridging position between the two metals. It has long been known that low-temperature photolysis of Ni-C yields distinc...
متن کاملCharacterization of a unique [FeS] cluster in the electron transfer chain of the oxygen tolerant [NiFe] hydrogenase from Aquifex aeolicus.
Iron-sulfur clusters are versatile electron transfer cofactors, ubiquitous in metalloenzymes such as hydrogenases. In the oxygen-tolerant Hydrogenase I from Aquifex aeolicus such electron "wires" form a relay to a diheme cytb, an integral part of a respiration pathway for the reduction of O(2) to water. Amino acid sequence comparison with oxygen-sensitive hydrogenases showed conserved binding m...
متن کاملA strenuous experimental journey searching for spectroscopic evidence of a bridging nickel–iron–hydride in [NiFe] hydrogenase
Direct spectroscopic evidence for a hydride bridge in the Ni-R form of [NiFe] hydrogenase has been obtained using iron-specific nuclear resonance vibrational spectroscopy (NRVS). The Ni-H-Fe wag mode at 675 cm(-1) is the first spectroscopic evidence for a bridging hydride in Ni-R as well as the first iron-hydride-related NRVS feature observed for a biological system. Although density function t...
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ورودعنوان ژورنال:
- Chemical communications
دوره 48 6 شماره
صفحات -
تاریخ انتشار 2012