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Biochim Biophys Acta. 2016 May;1857(5):522-530. doi: 10.1016/j.bbabio.2015.09.007. Epub 2015 Sep 28.

Electron transfer activity of a de novo designed copper center in a three-helix bundle fold.

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Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, United States.
Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris Sud, CNRS, 91405 Orsay Cedex, France.
iBiTec-S, CEA Saclay, Bât 532, 91191 Gif-sur-Yvette Cedex, France. Electronic address:
Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, United States. Electronic address:


In this work, we characterized the intermolecular electron transfer (ET) properties of a de novo designed metallopeptide using laser-flash photolysis. α3D-CH3 is three helix bundle peptide that was designed to contain a copper ET site that is found in the β-barrel fold of native cupredoxins. The ET activity of Cuα3D-CH3 was determined using five different photosensitizers. By exhibiting a complete depletion of the photo-oxidant and the successive formation of a Cu(II) species at 400 nm, the transient and generated spectra demonstrated an ET transfer reaction between the photo-oxidant and Cu(I)α3D-CH3. This observation illustrated our success in integrating an ET center within a de novo designed scaffold. From the kinetic traces at 400 nm, first-order and bimolecular rate constants of 10(5) s(-1) and 10(8) M(-1) s(-1) were derived. Moreover, a Marcus equation analysis on the rate versus driving force study produced a reorganization energy of 1.1 eV, demonstrating that the helical fold of α3D requires further structural optimization to efficiently perform ET. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.


Cupredoxin; De novo design; Laser-flash photolysis; Photoinduced electron transfer; Three-helix bundle

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