title: Stability, redox parameters and electrocatalytic activity of a cytochrome domain from a new subfamily.
abstract: We report a spectroscopic, electrochemical and spectroelectrochemical characterization of the soluble cytochrome c domain (Cyt-D) from the Rhodothermus marinus caa3 terminal oxygen reductase and its putative electron donor, a high potential [4Fe-4S] protein (HiPIP). Cyt-D exhibits superior stability, particularly at the level of the heme pocket, compared to archetypical cytochromes in terms of thermal and chemical denaturation, alkaline transition and oxidative bleaching of the heme, which is further increased upon adsorption on biomimetic electrodes. Therefore, this protein is proposed as a suitable building block for electrochemical biosensing. As a proof of concept, we show that the immobilized Cyt-D exhibits good electrocatalytic activity towards H2O2 reduction. Relevant thermodynamic and kinetic electron transfer parameters for Cyt-D and HiPIP are also reported, including reorganization energies of 0.33 eV and 0.42 eV, respectively.
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA Buenos Aires, Argentina.
authors.forename: María F
authors.initials: MF
authors.lastname: Molinas
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA Buenos Aires, Argentina.
authors.forename: Leandro
authors.initials: L
authors.lastname: Benavides
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA Buenos Aires, Argentina.
authors.forename: María A
authors.initials: MA
authors.lastname: Castro
authors.affiliation: Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, C1428EHA Buenos Aires, Argentina. Electronic address: dhmurgida@qi.fcen.uba.ar.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Murgida
mesh_terms: D002384:Catalysis; D003580:Cytochromes / Q000737:chemistry / Q000378:metabolism*; D055664:Electrochemical Techniques; D004795:Enzyme Stability; D007700:Kinetics; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: D003580:Cytochromes
keywords: Heme proteins; Hydrogen peroxide sensing; Iron–sulfur proteins; Protein electron transfer; SERR spectroelectrochemistry