ORCID Profile
0000-0003-4715-7200
Current Organisation
University of York
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Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC03870D
Abstract: A review of the insight into biological redox chemistry which has been enabled by the development of large litude Fourier transform ac voltammetry.
Publisher: American Chemical Society (ACS)
Date: 11-09-2007
DOI: 10.1021/CR050191U
Publisher: American Chemical Society (ACS)
Date: 19-01-2017
DOI: 10.1021/ACS.ANALCHEM.6B03589
Abstract: Rapid disulfide bond formation and cleavage is an essential mechanism of life. Using large litude Fourier transformed alternating current voltammetry (FTacV) we have measured previously uncharacterized disulfide bond redox chemistry in Escherichia coli HypD. This protein is representative of a class of assembly proteins that play an essential role in the biosynthesis of the active site of [NiFe]-hydrogenases, a family of H
Publisher: Frontiers Media SA
Date: 08-02-2018
Publisher: American Chemical Society (ACS)
Date: 08-2007
DOI: 10.1021/JA073643O
Publisher: Proceedings of the National Academy of Sciences
Date: 11-11-2015
Abstract: The mononuclear Mo enzymes are ubiquitous throughout life, and the notion that their activity arises from Mo(VI/V/IV) redox cycling is a central dogma of bioinorganic chemistry. We prove that YedY, a structurally simple mononuclear Mo enzyme, operates via a strikingly different mechanism: the catalytically active state is generated from addition of three electrons and three protons to the Mo(V) form of the enzyme, suggesting for the first time (to our knowledge) that organic-ligand–based electron transfer reactions at the pyranopterin play a role in catalysis. We showcase Fourier-transformed alternating-current voltammetry as a technique with powerful utility in metalloenzyme studies, allowing the simultaneous measurement of redox catalysis and the underlying electron transfer reactions.
Publisher: Elsevier BV
Date: 02-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B801144N
Abstract: This tutorial review describes studies of hydrogen production and oxidation by biological catalysts--metalloenzymes known as hydrogenases--attached to electrodes. It explains how the electrocatalytic properties of hydrogenases are studied using specialised electrochemical techniques and how the data are interpreted to allow assessments of catalytic rates and performance under different conditions, including the presence of O2, CO and H2S. It concludes by drawing some comparisons between the enzyme active sites and platinum catalysts and describing some novel proof-of-concept applications that demonstrate the high activities and selectivities of these 'alternative' catalysts for promoting H2 as a fuel.
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B508520A
Abstract: Hydrogenases provide an inspiration for future energy technologies. The active sites of these microbial enzymes contain Fe or Ni and Fe coordinated by CO and CN ligands: yet they have activities for hydrogen cycling that compare with Pt catalysts. Is there a future for enzymes in technological H2 cycling? There are obviously going to be disadvantages, perhaps overwhelming, as enzymes are notoriously fragile yet what are the positive aspects and can we learn any chemistry that might be applied to produce the electrolytic and fuel cell catalysts of the future? We have developed a suite of novel electrochemical experiments to probe the chemistry of hydrogenases. The reactions are controlled and monitored at the surface of a small electrode, and characteristic catalytic properties are discernible from tiny amounts of s le material, so this approach can be used to search the microbial world for the best catalysts. Although electrochemistry does not provide structural information directly, it does give a "road map" by which to navigate the pathways and conditions that lead to particular states of the enzymes. This has prompted many interdisciplinary collaborations with other scientists who have provided microbiological, spectroscopic and structural contexts for this work. This article describes how these electrochemical experiments are set up, the data are analysed, and the results interpreted. We have determined mechanisms of catalysis, electron transfer, activation and inactivation, and defined important properties such as O2 tolerance and CO resistance in physical terms. Using an O2-tolerant hydrogenase, we have demonstrated a "proof of concept" miniature fuel cell that will run on a mixed H2/O2 feed in aqueous solution.
Publisher: Elsevier BV
Date: 12-2011
Publisher: American Chemical Society (ACS)
Date: 11-04-2012
DOI: 10.1021/JA302096R
Abstract: Formaldehyde-a rapid and reversible inhibitor of hydrogen evolution by [FeFe]-hydrogenases-binds with a strong potential dependence that is almost complementary to that of CO. Whereas exogenous CO binds tightly to the oxidized state known as H(ox) but very weakly to a state two electrons more reduced, formaldehyde interacts most strongly with the latter. Formaldehyde thus intercepts increasingly reduced states of the catalytic cycle, and density functional theory calculations support the proposal that it reacts with the H-cluster directly, most likely targeting an otherwise elusive and highly reactive Fe-hydrido (Fe-H) intermediate.
Publisher: American Chemical Society (ACS)
Date: 12-2005
DOI: 10.1021/JA055160V
Abstract: A new strategy is described for comparing, quantitatively, the ability of hydrogenases to tolerate exposure to O2 and anoxic oxidizing conditions. Using protein film voltammetry, the inherent sensitivities to these challenges (thermodynamic potentials and rates of reactions) have been measured for enzymes from a range of mesophilic microorganisms. In the absence of O2, all the hydrogenases undergo reversible inactivation at various potentials above that of the H+/H2 redox couple, and H2 oxidation activities are thus limited to characteristic "potential windows". Reactions with O2 vary greatly the [FeFe]-hydrogenase from Desulfovibrio desulfuricans ATCC 7757, an anaerobe, is irreversibly damaged by O2, surviving only if exposed to O2 in the anaerobically oxidized state (which therefore affords protection). In contrast, the membrane-bound [NiFe]-hydrogenase from the aerobe, Ralstonia eutropha, reacts reversibly with O2 even during turnover and continues to catalyze H2 oxidation in the presence of O2.
Publisher: American Chemical Society (ACS)
Date: 26-07-2017
DOI: 10.1021/JACS.7B03611
Publisher: American Chemical Society (ACS)
Date: 08-01-2021
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Alison Parkin.