Enhanced oxygen-tolerance of the full heterotrimeric membrane-bound [NiFe]-hydrogenase of ralstonia eutropha.

Hydrogenases are oxygen-sensitive enzymes that catalyze the conversion between protons and hydrogen. Water-soluble subcomplexes of membrane-bound [NiFe]-hydrogenases (MBH) have been extensively studied for applications in hydrogen-oxygen fuel cells as they are relatively tolerant to oxygen, although even these catalysts are still inactivated in oxidative conditions. Here, the full heterotrimeric MBH of Ralstonia eutropha, including the membrane-integral cytochrome b subunit, was investigated electrochemically using electrodes modified with planar tethered bilayer lipid membranes (tBLM). Cyclic voltammetry and chronoamperometry experiments show that MBH, in equilibrium with the quinone pool in the tBLM, does not anaerobically inactivate under oxidative redox conditions. In aerobic environments, the MBH is reversibly inactivated by O2, but reactivation was found to be fast even under oxidative redox conditions. This enhanced resistance to inactivation is ascribed to the oligomeric state of MBH in the lipid membrane

New trends in enzyme immobilization at nanostructured interfaces for efficient electrocatalysis in biofuel cells

International audienceBiofuel cells, and among them enzymatic biofuel cells, are expected to take part in a sustainable economy in a next future. The development of such biodevices requires significant improvements in terms of efficiency of enzyme immobilization at the electrodes, so as to enable direct electron transfer, and to increase and stabilize the current densities. Many works during the last years aimed at reaching higher current densities, thus power densities, while increasing the long term stability of the enzymatic bioelectrodes. Search for new enzymes, wild type or mutants, new entrapment procedures, but also new electrode architectures, have been targeted. This review focuses on the materials developed and involved during the last few years to meet these demands via nanostructuration of electrode interfaces. Discussion is essentially focused on cases where direct electron transfer between enzymes and electrochemical interfaces are involved. After having introduced the main reasons for the need of nanostructuration, the materials and methods that are newly developed are described. The consequences on improved performances for enzymatic bioelectrodes are discussed, and finally major challenges for future research are addressed

Design of a H2/O2 biofuel cell based on thermostable enzymes

A new generation of mediatorless H2/O2 biofuel cells was designed based on a hyperthermophilic O2-tolerant hydrogenase and a thermostable bilirubin oxidase both immobilized on carbon nanofibers. A power density up to 1.5±0.2 mW*cm−2 at 60 °Cwas reached. This first demonstration of a H2/O2 biofuel cell able to deliver electricity over awide range of temperatures, from30 °C up to 80 °C, and over a large pHwindow, allows considering this device as an alternative power supply for small portable applications in various environments, including extreme ones

How to advance the frontiers of current biofuel cells: design of a H2/O2 biofuel cell based on thermostable enzymes

International audienceA new generation of mediatorless H2/O2 biofuel cells was designed based on a hyperthermophilic O2-tolerant hydrogenase and a thermostable bilirubin oxidase both immobilized on carbon nanofibers. A power density up to 1.5 ± 0.2 mW.cm-2 at 60°C was reached. This first demonstration of a H2/O2 biofuel cell able to deliver electricity over a wide range of temperatures, from 30°C up to 80°C, and over a large pH window, allows considering this device as an alternative power supply for small portable applications in various environments, including extreme ones

An innovative powerful and mediatorless H2/O2 biofuel cell based on an outstanding bioanode

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Synthesis and enzymatic photo-activity of an O2 tolerant hydrogenase-CdSe@CdS quantum rod bioconjugate.

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How to advance the frontiers of current biofuel cells: design of a H2/O2 biofuel cell based on thermostable enzymes

International audienceA new generation of mediatorless H2/O2 biofuel cells was designed based on a hyperthermophilic O2-tolerant hydrogenase and a thermostable bilirubin oxidase both immobilized on carbon nanofibers. A power density up to 1.5 ± 0.2 mW.cm-2 at 60°C was reached. This first demonstration of a H2/O2 biofuel cell able to deliver electricity over a wide range of temperatures, from 30°C up to 80°C, and over a large pH window, allows considering this device as an alternative power supply for small portable applications in various environments, including extreme ones

Reconstitution of supramolecular organization involved in energy metabolism at electrochemical interfaces for biosensing and bioenergy production

International audienceHow the redox proteins and enzymes involved in bioenergetic pathways are organized is a relevant fundamental question, but our understanding of this is still incomplete. This review provides a critical examination of the electrochemical tools developed in recent years to obtain knowledge of the intramolecular and intermolecular electron transfer processes involved in metabolic pathways. Furthermore, better understanding of the electron transfer processes associated with energy metabolism will provide the basis for the rational design of biotechnological devices such as electrochemical biosensors, enzymatic and microbial fuel cells, and hydrogen production factories. Starting from the redox complexes involved in two relevant bacterial chains, i.e., from the hyperthermophile Aquifex aeolicus and the acidophile Acidithiobacillus ferrooxidans, examination of protein–protein interactions using electrochemistry is first reviewed, with a focus on the orientation of a protein on an electrochemical interface mimic of a physiological interaction between two partners. Special attention is paid to current research in the electrochemistry of essential membrane proteins, which is one mandatory step toward the understanding of energy metabolic pathways. The complex and challenging architectures built to reconstitute a membrane-like environment at an electrode are especially considered. The role played by electrochemistry in the attempt to consider full bacterial metabolism is finally emphasized through the study of whole cells immobilized at electrodes as suspensions or biofilms. Before the performances of biotechnological devices can be further improved to make them really attractive, questions remain to be addressed in this particular field of research. We discuss the bottlenecks that need to be overcome in the future

A friendly detergent for H2 oxidation by Aquifex aeolicus membrane-bound hydrogenase immobilized on graphite and Self-Assembled-Monolayer-modified gold electrodes

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