INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Alternative ground states enable pathway switching in biological electron transfer
LUCIANO A. ABRIATA; DAMIÁN ÁLVAREZ-PAGGI; GABRIELA N. LEDESMA; NINIAN J. BLACKBURN; ALEJANDRO J. VILA; DANIEL H. MURGIDA
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
NATL ACAD SCIENCES
Lugar: Washington DC, USA; Año: 2012 vol. 109 p. 17348 - 17348
Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or invisible electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which proteinprotein interactions and membrane potential may optimize and regulate electronproton energy transduction.