Abstract
Hydrogenases are enzymes of great biotechnological relevance because they catalyse the interconversion of H2, water (protons) and electricity using non-precious metal catalytic active sites. Electrochemical studies into the reactivity of NiFe membrane-bound hydrogenases (MBH) have provided a particularly detailed insight into the reactivity and mechanism of this group of enzymes. Significantly, the control centre for enabling O2 tolerance has been revealed as the electron-transfer relay of FeS clusters, rather than the NiFe bimetallic active site. The present review paper will discuss how electrochemistry results have complemented those obtained from structural and spectroscopic studies, to present a complete picture of our current understanding of NiFe MBH.
Highlights
Humankind’s current fossil fuel economy is unsustainable: it is non-renewable, generates the greenhouse gas carbon dioxide and relies on finite resources which are not evenly distributed across the globe, creating geo- and political- access issues [1]
Enormous progress has been made in recent years to understand the origin of O2 tolerance in membrane-bound hydrogenases (MBH), and the essential roles of redox centres and residues remote from the NiFe active site have been elucidated and understood
There remain some core aspects of NiFe MBH biochemistry, such as the origin of catalytic bias and the structure of the Ni-A state, formed when O2 sensitive enzymes react with O2, which remain elusive
Summary
Humankind’s current fossil fuel economy is unsustainable: it is non-renewable, generates the greenhouse gas carbon dioxide and relies on finite resources which are not evenly distributed across the globe, creating geo- and political- access issues [1]. In comparison with the use of fossil fuels, a renewable H2 fuel economy presents many advantages: generating H2 from water is a cyclical, sustainable process, and vehicular H2 technology is a commercial reality [2]. + 2e − ) to achieve the overall reaction of solar driven water splitting (H2O + hν → H2 O2) [3]. There is a requirement for highly efficient catalysts built from commonly available elements that combine protons and electrons to produce H2. Hydrogenases are stable in water, built from earthabundant elements and have high substrate affinities and fast turnover rates [6], and these combined factors have fuelled an interest into how hydrogenases can be utilized within a future
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