Reversible Switching of Redox-Active Molecular Orbitals and Electron Transfer Pathways in CuA Sites of Cytochrome c Oxidase

ZITARE U.; ALVAREZ PAGGI, D.; MORGADA M.; ABRIATA, L.A.; VILA, A.J.; MURGIDA, D.H.

Angewandte Chemie

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2015 vol. 54 p. 9555 - 9559

1433-7851

The CuA site of cytochrome c oxidase is a redox hubthat participates in rapid electron transfer at low driving forceswith two redox cofactors in nearly perpendicular orientations.Spectroscopic and electrochemical characterizations performedon first and second-sphere mutants have allowed usto experimentally detect the reversible switching between twoalternative electronic states that confer different directionalitiesto the redox reaction. Specifically, the M160H variant ofa native CuA shows a reversible pH transition that allows tofunctionally probe both states in the same protein species.Alternation between states exerts a dramatic impact on thekinetic redox parameters, thereby suggesting this effect as themechanism underlying the efficiency and directionality of CuAelectron transfer in vivo. These findings may also prove usefulfor the development of molecular electronics.