title: Laccase bioelectrocatalyst at a steroid-type biosurfactant-modified carbon nanotube interface.
abstract: Achieving oxygen reduction at high positive potentials with fast heterogeneous electron transfer is desirable for the biocathode of fuel cells based on enzymes. Here, we present an effective interface for obtaining direct electron transfer from a laccase (Lac)-based cathode for O2 reduction, starting from a potential very close to the redox equilibrium potential of the oxygen/water couple. The interface between Lac and single-walled carbon nanotubes was improved by modification with the steroid biosurfactant sodium cholate. The heterogeneous electron-transfer rate between the type-1 Cu site of Lac and the modified electrode was determined to be 3000 s(-1). The electron-transfer rate was sensitive to the side chain of the steroid biosurfactant, and the rate decreased more than 10-fold when sodium deoxycholate was used as the side chain.
authors.affiliation: †Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.|‡Kumamoto Institute for Photo-Electro Organics, Kumamoto 862-0901, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Tominaga
authors.affiliation: †Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: †Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Togami
mesh_terms: D055162:Biocatalysis; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D004579:Electron Transport; D042845:Laccase / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D011487:Protein Conformation; D020358:Sodium Cholate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D055454:Trametes / Q000201:enzymology; D014867:Water / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D013501:Surface-Active Agents; D014867:Water; D042845:Laccase; D020358:Sodium Cholate; D010100:Oxygen