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|Title:||Proton Transfer in the Catalytic Cycle of [NiFe] Hydrogenases: Insight from Vibrational Spectroscopy.|
|Authors:||Ash, Philip A.|
Vincent, Kylie A.
|Publisher:||American Chemical Society|
|Citation:||ACS Catalysis, 2017, 7 (4), pp. 2471-2485|
|Abstract:||Catalysis of H2 production and oxidation reactions is critical in renewable energy systems based around H2 as a clean fuel, but the present reliance on platinum-based catalysts is not sustainable. In nature, H2 is oxidized at minimal overpotential and high turnover frequencies at [NiFe] catalytic sites in hydrogenase enzymes. Although an outline mechanism has been established for the [NiFe] hydrogenases involving heterolytic cleavage of H2 followed by a first and then second transfer of a proton and electron away from the active site, details remain vague concerning how the proton transfers are facilitated by the protein environment close to the active site. Furthermore, although [NiFe] hydrogenases from different organisms or cellular environments share a common active site, they exhibit a broad range of catalytic characteristics indicating the importance of subtle changes in the surrounding protein in controlling their behavior. Here we review recent time-resolved infrared (IR) spectroscopic studies and IR spectroelectrochemical studies carried out in situ during electrocatalytic turnover. Additionally, we re-evaluate the significant body of IR spectroscopic data on hydrogenase active site states determined through more conventional solution studies, in order to highlight mechanistic steps that seem to apply generally across the [NiFe] hydrogenases, as well as steps which so far seem limited to specific groups of these enzymes. This analysis is intended to help focus attention on the key open questions where further work is needed to assess important aspects of proton and electron transfer in the mechanism of [NiFe] hydrogenases.|
|Rights:||Copyright © the authors, 2017. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.|
|Description:||The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acscatal.6b03182. Illustrative use of Nia-C as an internal standard, stereo view showing the position of crystallographically ordered water molecules in the vicinity of the [NiFe] hydrogenase active site (PDF) pdf cs6b03182_si_001.pdf (602.55 kb)|
|Appears in Collections:||Published Articles, Dept. of Chemistry|
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