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Reversible Switching of Redox‐Active Molecular Orbitals and Electron Transfer Pathways in Cu A Sites of Cytochrome c Oxidase
Author(s) -
Zitare Ulises,
AlvarezPaggi Damián,
Morgada Marcos N.,
Abriata Luciano A.,
Vila Alejandro J.,
Murgida Daniel H.
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201504188
Subject(s) - redox , electron transfer , chemistry , electrochemistry , electron transport chain , cytochrome c oxidase , photochemistry , half reaction , cofactor , crystallography , chemical physics , enzyme , inorganic chemistry , electrode , biochemistry
The Cu A site of cytochrome c oxidase is a redox hub that participates in rapid electron transfer at low driving forces with two redox cofactors in nearly perpendicular orientations. Spectroscopic and electrochemical characterizations performed on first and second‐sphere mutants have allowed us to experimentally detect the reversible switching between two alternative electronic states that confer different directionalities to the redox reaction. Specifically, the M160H variant of a native Cu A shows a reversible pH transition that allows to functionally probe both states in the same protein species. Alternation between states exerts a dramatic impact on the kinetic redox parameters, thereby suggesting this effect as the mechanism underlying the efficiency and directionality of Cu A electron transfer in vivo. These findings may also prove useful for the development of molecular electronics.