Hydrogenases as catalysts for fuel cells: Strategies for efficient immobilization at electrode interfaces

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

“…In periplasmic O 2 -sensitive [NiFe]-Hases, an anionic patch of amino acid residues, mainly glutamate residues, surrounds the FeS distal cluster. [88,162] A high dipole moment points towards this cluster. [163] This polarity allows a physiological electrostatic recognition with the positive tetrahemic cytochrome c 3 .…”

“…[83,84] Whereas in the late 80s, electrochemistry provided essential kinetic data for Hases and their physiological partners, [85][86][87][88] Yoropolov's group, followed by Hagen's then Armstrong's groups demonstrated that Hases could yield a direct current for H 2 oxidation or proton reduction when adsorbed at graphite electrodes. [83,84,88,89] The influences of parameters such as pH, temperature, gas composition, and graphite polishing procedure were evaluated, [89][90][91] before fundamental research was undertaken to understanding of the catalytic properties of this exciting enzyme. Essential kinetic data were then available to support the spectroscopic data.…”

Electrochemistry, AFM, and PM‐IRRA Spectroscopy of Immobilized Hydrogenase: Role of a Hydrophobic Helix in Enzyme Orientation for Efficient H2 Oxidation

“…Mediated electron transfer (MET) allowed recreation of the physiological electron-transfer chain, and/or connection of unfavorably oriented enzymes. [2][3][4][5][6] Previous work demonstrated that DET or MET processes for H 2 oxidation by a soluble, O 2 -sensitive [NiFe] Hase from Desulfovibrio species could be controlled by electrostatic interaction. [7] The presence of an acidic patch of amino acids, coupled to a dipole moment pointing towards the distal FeS cluster (positioned at the surface of the enzyme), allowed orientation of the enzyme, which turned upside down as a function of the charge on the electrochemical interface.…”

Nanostructured Inorganic Materials at Work in Electrochemical Sensing and Biofuel Cells

“…13 Å (a major hindrance for DET). To make DET happen, there are two minimal prerequisites that must be accommodated [14,17,47,48]: (i) the distance between the electron donor and acceptor, i.e., a cofactor and an electrode undergoing heterogeneous electron transfer, should not exceed 2 nm (20 Å) since greater distances lead to negligible rates of electron transfer; (ii) the cofactor must be orientated towards the electrode to keep the electron tunneling distance below 2 nm in the case of an enzyme possessing a cofactor which is of a sufficient proximal location. By offering an electrode surface that entraps and encompasses the enzyme, mesoporous electrode materials are of particular interest, as well as carbon nanotubes which provide suitable orientation for enzyme immobilization and establish a connection between the electrode surface and the deeply buried active site of the enzyme.…”