Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.712076
Title: Inhibition of [NiFe]-hydrogenases with π-acid ligands : electrochemical and in situ infrared spectroelectrochemical studies
Author: Chung, Min-Wen
ISNI:       0000 0004 6062 5547
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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Abstract:
Hydrogenases are of great interest because they utilise abundant and inexpensive metals, Fe or Ni-Fe, in their active sites to catalyse hydrogen cycling - highly relevant to enzyme-based or bio-inspired technologies. The Fe in the active site is in a biologically unusual ligand environment coordinated by CO and CN-. These small molecule ligands have intense infrared absorption features and serve as good probes to monitor the coordination state and electronic environment of the active site. Infrared spectroscopy has therefore become a standard approach for characterising hydrogenases isolated from different organisms, but to date only few spectroscopic results have been correlated with states of the active site generated during catalysis. A new approach, PFIRE, which couples direct electrochemical control of hydrogenase, immobilised on a carbon particle electrode, and FTIR spectroscopy together is exploited in this Thesis to address this issue. This Thesis develops a surfactant-modified particle electrode to have a high loading of E. coli Hyd-2 (a standard [NiFe]-hydrogenase) for use in PFIRE for comparison with the O2-tolerant membrane-bound hydrogenase, E. coli Hyd-1, during catalytic turnover. A systematic study of how E. coli Hyd-1 and E. coli Hyd-2 respond to other ?-acid ligands is also reported in this Thesis. Cyanide was found to have unusual reactions with Hyd-1 and Hyd-2; it can promote the formation of the oxidised inactive state, Ni B. Isocyanides are shown for the first time as inhibitors of [NiFe]-hydrogenases. The use of bulky isocyanides as probes in this Thesis reveals that the catalytic pocket of Hyd-1 is more spacious than previously thought, as even n-butyl isocyanide with a long tail is capable of getting in and out to react with the active site reversibly. Overall this Thesis provides a view of how pi-acid ligands react with a prototype O2-sensitive and O2-tolerant [NiFe]-hydrogenase.
Supervisor: Vincent, Kylie Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.712076  DOI: Not available
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