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

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


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 protein-protein interactions and membrane potential may optimize and regulate electron-proton energy transduction.

Original languageEnglish (US)
Pages (from-to)17348-17353
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number43
StatePublished - Oct 23 2012


  • Cytochrome oxidase
  • Invisible states
  • NMR
  • Paramagnetic proteins
  • Spectroscopy

ASJC Scopus subject areas

  • General


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