title: Electron transfer dynamics of Rhodothermus marinus caa3 cytochrome c domains on biomimetic films.
abstract: The subunit II of the caa(3) oxygen reductase from Rhodothermus marinus contains, in addition to the Cu(A) center, a c-type heme group in the cytochrome c domain (Cyt-D) that is the putative primary electron acceptor of the enzyme. In this work we have combined surface-enhanced resonance Raman (SERR) spectroelectrochemistry, molecular dynamics (MD) simulations and electron pathway calculations to assess the most likely interaction domains and electron entry/exit points of the truncated Cyt-D of subunit II in the reactions with its electron donor, HiPIP and electron acceptor, Cu(A). The results indicate that the transient interaction between Cyt-D and HiPIP relies upon a delicate balance of hydrophobic and polar contacts for establishing an optimized electron transfer pathway that involves the exposed edge of the heme group and guaranties efficient inter-protein electron transfer on the nanosecond time scale. The reorganization energy of ca. 0.7 eV was determined by time-resolved SERR spectroelectrochemistry. The intramolecular electron transfer pathway in integral subunit II from Cyt-D to the Cu(A) redox center most likely involves the iron ligand histidine 20 as an electron exit point in Cyt-D.
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: Maria F
authors.initials: MF
authors.lastname: Molinas
authors.forename: Ariel
authors.initials: A
authors.lastname: De Candia
authors.forename: Sergio H
authors.initials: SH
authors.lastname: Szajnman
authors.forename: Juan B
authors.initials: JB
authors.lastname: Rodríguez
authors.forename: Marcelo
authors.initials: M
authors.lastname: Martí
authors.forename: Manuela
authors.initials: M
authors.lastname: Pereira
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
authors.forename: Smilja
authors.initials: S
authors.lastname: Todorovic
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Murgida
mesh_terms: D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D045264:Cytochromes a / Q000737:chemistry / Q000378:metabolism*; D045266:Cytochromes a3 / Q000737:chemistry / Q000378:metabolism*; D004579:Electron Transport; D056004:Molecular Dynamics Simulation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D045245:Rhodothermus / Q000201:enzymology*; D013059:Spectrum Analysis, Raman
chemical_list: D003574:Cytochrome c Group; D045266:Cytochromes a3; D021122:Protein Subunits; C435384:cytochrome caa(3); D045264:Cytochromes a