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

详细信息    查看全文

• 作者：Jefferson S. Plegaria^a ; Christian Herrero^b ; Annamaria Quaranta^c ; ^{Annamaria.QUARANTA@cea.fr" class="auth_mail" title="E-mail the corresponding author} ; Vincent L. Pecoraro^a ; ^{vlpec@umich.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：De novo design ; Cupredoxin ; Three-helix bundle ; Photoinduced electron transfer ; Laser-flash photolysis
• 刊名：Biochimica et Biophysica Acta (BBA) - Bioenergetics
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：1857
• 期：5
• 页码：522-530
• 全文大小：1215 K

文摘

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 10⁵ s^− 1 and 10⁸ 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.