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Operando FTIR spectro-electrochemistry of hydrogenases: unraveling the basis of biological H2 production for innovative clean energy technologies

Periodic Reporting for period 1 - H2Bio2Energy (Operando FTIR spectro-electrochemistry of hydrogenases: unraveling the basis of biological H2 production for innovative clean energy technologies)

Reporting period: 2018-01-08 to 2020-01-07

The problem/issue being addressed: The project H2Bio2Energy addresses fundamental questions on how enzymes produce hydrogen. This reaction naturally occurs in some microorganisms and leads to the generation of this valuable gas that can be used as a fuel for clean technological applications.
Importance for society: The impact of using fossil fuels to sustain the modern society comes with several detrimental effects that include the depletion of these non-renewable resources, environmental pollution and consequent climate change. Effective innovation in the energy industry relies on the development of novel technologies that are based on renewable resources, and hydrogen production is one of the forefronts of this research. Learning from the highly efficient way that nature produces hydrogen will allow us to copy and develop bio-inspired processes that will contribute to the growing demand for sustainable energy in the future.
Overall objectives: The main objective is to develop innovative experimental approaches that provide information on how enzymes named [FeFe]-hydrogenases naturally produce hydrogen. The exact reaction mechanism is not fully understood, and this information will be essential to exploit these enzymes in future technologies and/or to design more efficient artificial catalysts.
Overview of the results:
1) The project has provided extensive training to the Fellow on innovative infrared techniques (FTIR) applied to metalloenzymes and a productive two-way transfer of knowledge with the host group.
2) Protein Film IR Electrochemistry (PFIRE) has been applied for the first time to [FeFe]-hydrogenases. The technique allows for simultaneous investigation of functional and spectroscopic features during catalytic turnover of redox enzymes. The results obtained show feasibility of this approach and set the basis for future more detailed investigation.
3) Custom-built spectro-electrochemical equipment allowed mechanistic investigation on the role of proton transfer within [FeFe]-hydrogenases, and how this influences the redox equilibria at the active site.
4) FTIR micro-spectroscopy was used to investigate how these enzymes respond when in the crystalline state. This work showed that the enzymes retain their natural reactivity when crystallised and that these features can easily be controlled during the experiment. This provides a powerful tool for controlling and determining the exact redox state of the sample under given conditions and opens completely new perspectives in structural biology.
Exploitation and dissemination:
The results have been presented to the following national meetings and international conferences:
- Hydrogenase workshop, Berlin, Germany, 2018.
- European Biological Inorganic Chemistry Conference (EuroBIC), Birmingham, UK, 2018.
- International Hydrogenase Conference in Lisbon, Portugal, 2019.
- Royal Society of Chemistry Dalton Division Southern Regional Meeting in Oxford, UK, 2019.
The Fellow is now preparing two manuscripts for publication in peer-reviewed scientific journals describing the results of the project.
The recent years have seen an unprecedented growth in the information regarding [FeFe]-hydrogenase mechanism of action, but many details and key information are still missing. This project provides new tools for looking into these enzymes and adds novel details to the catalytic mechanism. In particular, the development of FTIR micro-spectroscopy techniques sets the basis for detailed structural investigation. Currently, matching spectroscopic and functional information with structures is a complex task in this field. The results obtained here show that this can be easily achieved and opens new horizons towards elucidating each of the key steps in the reaction mechanism.
This project contributes to the fundamental understanding of natural reactions that can be exploited for useful industrial purposes. The main impact is within the scientific community and it is aimed at scientists that can engineer these enzymes to improve their performances or try to mimic their efficient features to design novel synthetic catalysts based on cheap and abundant metals (such as iron) instead of expensive and rare elements (such as platinum).