Characterization of Shewanella oneidensis MtrC: a cell-surface decaheme cytochrome involved in respiratory electron transport to extracellular electron acceptors

MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV–vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately -500 mV (vs. the standard hydrogen electrode). Across this potential window the UV–vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled low-spin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate

Raman and Ftir Spectral Investigations of Twinned M(IO3)2 (M = Mn, Ni, Co, AND Zn) Crystals

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Sol-gel processed BaTiO3 : structural evolution from the gel to the crystalline powder

An amorphous solid, precursor to BaTiO3, has been prepared by the sol-gel route and its structural organization studied by LAXS as a function of temperature. In the low-temperature solid, the barium atoms keep the same environment as in barium acetate. The titanium alkoxide reacts with acetic acid to give an hexanuclear molecule

pH-Controlled Change of the Metal Coordination in a Dicopper(II) Complex of the Ligand H−BPMP: Crystal Structures, Magnetic Properties, and Catecholase Activity

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Développement de luminophores et revêtements composites sans terres rares à base de borate d’aluminium.

International audienc

Intramolecular Hg⋯π interactions of d-character with non-bridging atoms in mercury–aryl complexes

International audienceMercury 5d-orbitals are involved in intramolecular π-interactions with carbon and sulfur nearest and next-nearest neighbors in mercury–aryl complexes. This unexpected character of the electron cloud of mercury was revealed by high energy-resolution XANES spectroscopy readily interpreted in terms of a final-state local (l,m)-projected density of states (DOS)

New generation of aluminum borate phosphors for white LEDs lighting prepared by the polymeric precursor method

National audienc

New generation of aluminum borate phosphors for white LEDs lighting prepared by the polymeric precursor method

National audienc

Development of rare earth-free aluminium borate-based phosphors and composite films.

International audienc