NDLI: Peptide-based $FeS_{4}$ complexes: the zinc ribbon fold is unsurpassed to stabilize both the $Fe^{II}$ and $Fe^{III}$ states

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Jacques, Aurélie Latour, Jean-marc Sénèque, Olivier
Description	Author Affiliation: Jacques A ( CNRS, UMR 5249, LCBM, 17 rue des Martyrs, F-38054 Grenoble, France. olivier.seneque@cea.fr.)
Abstract	Whereas $Zn(Cys)_{4}$ zinc fingers exist with different protein folds, only the zinc ribbon fold is found in rubredoxin $Fe(Cys)_{4}$ sites. To assess the significance of this observation, we have investigated the binding and stability of $Fe^{2+}$ and $Fe^{3+}$ ions by a set of four peptides designed to model $Zn(Cys)_{4}$ zinc fingers with various folds, i.e. zinc ribbon, treble clef and a loosened zinc ribbon fold. All peptides were shown by means of UV-Vis and CD spectroscopies to form stable 1:1 $Fe^{II}/peptide$ complexes with binding constants higher than $10^{7}$ $M^{−1}$ at pH 7. Their oxidation into $Fe^{III}$ complexes and the stability of the latter were compared. The UV-Vis absorption and CD spectroscopic properties of the $Fe^{II}$ and $Fe^{III}$ complexes were analysed with respect to the structures of the zinc analogues in order to get insight into the local arrangement of the $Fe(Cys)_{4}$ core around the metal ion. The chemical stability of these complexes was rationalized according to the shielding from the solvent provided by the various peptide folds to the $FeS_{4}$ core. In addition, we showed that whereas UV-visible spectra inform only on the $FeS_{4},$ the information derived from the corresponding CD spectra extend to the $C_{β}$ orientation and the peptide fold. The results presented here demonstrate that while the zinc ribbon fold is not strictly required to obtain a $Fe(Cys)_{4}$ site, it affords a drastically superior protection of the site toward external redox agents. This finding brings new clues to engineer stable and redox-active $Fe(Cys)_{4}$ sites in de novo proteins.
ISSN	14779226
Issue Number	10
Volume Number	43
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2014-03-14
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Coordination Complexes Chemistry Iron Peptides Zinc Cysteine Zinc Fingers Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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