DS0205 -

Designing enzyme orientation for long duration enzymatic fuel cells – Enzymor

Submission summary

Enzymes are very efficient biocatalysts that convert a large panel of substrates in a large diversity of environments. Some of them contain redox cofactors composed of non noble metals such as iron or nickel that are required for their energy sources. Once immobilized on conductive supports, these redox enzymes can favorably replace rare and expensive platinum-based catalysts in devices such as fuel cells. Thanks to the current research concerning H2 production from renewable sources including biomass fermentation or enzymatic splitting of water, H2/O2 biofuel cell can thus be considered as a fully “green” device for electricity generation, with nogreenhouse gases emission.
The ENZYMOR project aims to elucidate the molecular mechanisms that control the efficiency of enzyme in the immobilized state which are required to enhance both the stability and performances of the biotechnological devices. It thus fits the requirement of the 2016 ANR call- Defi 2 “Energie Propre, Sure et Efficace” in the Axis 5 “H2 and fuel cell”, within the priority N°9 contributing to the decrease of platinum dependency.
Although efficient enzymes for H2 oxidation and O2 reduction are identified and the catalytic mechanisms in homogeneous and heterogeneous phases are quite well described, a cartography of the enzymes effectively participating to the catalysis in the immobilized state is not available. The conformation of the immobilized enzymes and the variation of this conformation as a function of parameters such as the electric field, pH, ionic strenght, covalent binding are largely unknown. Because they are few nanometers size macromolecular objects, the rate of the interfacial electron transfer relies on the proper structural orientation of the enzymes on the electrode. However no tools are available yet to discriminate between the different orientation states and to correlate with the enzymatic activity. Besides, one of the main drawbacks of enzymes against chemical catalysts is the lower coverage and stability. Once more, a set up able to quantify and optimize the amount of enzyme participating to the current, then to be able to discriminate, then to remediate, between the different sources of unstability is required.
These are the main objectives of ENZYMOR which unites electrochemists, spectroscopists, and theoretical chemists to develop new required experimental setups and define the molecular basis for efficient enzyme immobilization, including optimized electron transfer rates, reduced biomolecule loading and increased stability with time and under turn-over. The unique coupling of surface analytical tools (Polarization Modulated Infrared Reflection Absorption Spectroscopy, Surface Plasmon Resonance, Quartz Crystal Microbalance) with electrochemistry and dynamic modeling on fucntionalized electrodes will give access to the spatio-temporal and structural resolution of the immobilized enzymes. This will allow to rationally design electrochemical interfaces optimized for the electrical connection and stability of bioavailable and biodegradable enzymes.
The fundamental results obtained through ENZYMOR will be applied to the H2/O2 biofuel cells but will be applicable to any other devices based on enzyme immobilization on electrochemical interfaces, such as bioreactors, enzymatic H2 production or CO2 consumption.But beyond the applicative perspectives, the ENZYMOR project will first and foremost allow generating new knowledge toward the fundamental understanding of reconstituted metabolic electron transfer chains.

Project coordination

Elisabeth LOJOU (Centre National de la Recherche Scientifique Délégation Provence et Corse _Bioénergétique et Ingeniérie des Protéines)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CNRS DR12 _BIP UMR7281 Centre National de la Recherche Scientifique Délégation Provence et Corse _Bioénergétique et Ingeniérie des Protéines
CBMN UMR5248 Laboratoire de chimie, biologie des membranes et nanoobjets
LBT Laboratoire de Biochimie Théorique CNRS UPR 9080

Help of the ANR 496,122 euros
Beginning and duration of the scientific project: December 2016 - 48 Months

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