title: Preliminary electrochemical studies of the flavohaemoprotein from Ralstonia eutropha entrapped in a film of methyl cellulose: Activation of the reduction of dioxygen.
abstract: A flavohaemoprotein (FHP) from Ralstonia eutropha, obtained in a pure and active form, has been entrapped in a film of methyl cellulose on the electrode surface and gives a stable and reproducible electrochemical response at pH 7.00 when subject to cyclic voltammetry using a glassy carbon electrode. To our knowledge, no previous direct electrochemistry had been achieved with a bacterial flavohaemoglobin, which possess both a FAD and a haem. A single couple is observed which is assigned to the haem moiety of the protein, since the same result is obtained with a semi-apo form of the protein deprived of FAD (semi-apo FHP). The data collected were further confirmed by potentiometry with a platinum electrode, and the homogeneous electron transfer rate estimated by double potential step chronocoulometry at a bare glassy carbon electrode in the presence of methyl viologen (MV). The presence of FAD in the holoprotein is easily confirmed by UV-Vis spectrophotometry, but its expected electron relay role remains elusive. The protein activates the reduction of dioxygen by about 400 mV, the reduction current being proportional to the concentration of dioxygen up to 10% in volume in the gas mixture.
authors.affiliation: Laboratoire de Chimie Physique, UMR 8000 CNRS, Faculté des Sciences d'Orsay Université Paris-Sud XI, Bât 350, 15 rue Georges Clemenceau, 91405 Orsay Cedex, France. pedro.deoliveira@lcp.u-psud.fr
authors.forename: Pedro
authors.initials: P
authors.lastname: de Oliveira
authors.forename: Alireza
authors.initials: A
authors.lastname: Ranjbari
authors.forename: Laura
authors.initials: L
authors.lastname: Baciou
authors.forename: Tania
authors.initials: T
authors.lastname: Bizouarn
authors.forename: Gabriela
authors.initials: G
authors.lastname: Ollesch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ermler
authors.forename: Pierre
authors.initials: P
authors.lastname: Sebban
authors.forename: Bineta
authors.initials: B
authors.lastname: Keita
authors.forename: Louis
authors.initials: L
authors.lastname: Nadjo
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002482:Cellulose / Q000737:chemistry*; D020118:Cupriavidus necator / Q000737:chemistry*; D004563:Electrochemistry; D006420:Hemeproteins / Q000737:chemistry* / Q000378:metabolism*; D008745:Methylation; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012996:Solutions; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D006420:Hemeproteins; D012996:Solutions; C086193:flavohemoprotein, Bacteria; D002482:Cellulose; D010100:Oxygen