title: Electron transfer activity of a de novo designed copper center in a three-helix bundle fold.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, United States.
authors.forename: Jefferson S
authors.initials: JS
authors.lastname: Plegaria
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris Sud, CNRS, 91405 Orsay Cedex, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Herrero
authors.affiliation: iBiTec-S, CEA Saclay, Bât 532, 91191 Gif-sur-Yvette Cedex, France. Electronic address: Annamaria.QUARANTA@cea.fr.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Quaranta
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, United States. Electronic address: vlpec@umich.edu.
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Pecoraro
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001400:Azurin / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004734:Energy Metabolism; D006801:Humans; D008958:Models, Molecular; D010970:Plastocyanin / Q000737:chemistry* / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; C050107:cupredoxin; C012543:rusticyanin; D001400:Azurin; D003300:Copper; D010970:Plastocyanin
keywords: Cupredoxin; De novo design; Laser-flash photolysis; Photoinduced electron transfer; Three-helix bundle