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Electron transfer reactions of methionine peptides with photochemically generated ruthenium(III)–polypyridyl complexes

Paper ID Volume ID Publish Year Pages File Format Full-Text
26503 43956 2014 9 PDF Available
Title
Electron transfer reactions of methionine peptides with photochemically generated ruthenium(III)–polypyridyl complexes
Abstract

•Ru3+ is generated photochemically from Ru2+.•Ru3+ oxidizes peptide containing methionines to the corresponding sulfoxides.•The oxidation proceeds through electron transfer mechanism.•The observation of methionine sulfide cation radical as the transient from the laser flash photolysis study supports the operation electron transfer mechanism.•The kinetic data are in accordance with the ΔG° values of the reaction.

The dynamics of the oxidation of five methionine carrying peptides with six Ru(III)–polypyridyl complexes in aqueous acetonitrile medium have been followed by spectrophotometric technique. The electron transfer (ET) reaction of [Ru(NN)3]3+ complex (NN = polypyridyl ligand) with peptide containing methionine is sensitive to the change in the structure of ligand of Ru(III) complex and N-terminal component of the peptide Met-Gly Met-Ala Met-Ser Met-Val and Met-Leu. The reaction follows the overall second-order kinetics, first order each in the oxidant and the substrate. Based on the substituent and solvent effects, an outer-sphere electron transfer from the sulfur center of the peptide to Ru(III) has been proposed as the rate controlling step of the reaction. The ET nature of the reaction is confirmed from the recorded transient absorption spectrum of peptide containing methionine sulfur radical cation by laser flash photolysis technique. Marcus theory is successfully applied to the ET reaction.

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Keywords
Peptide containing methionine; Ruthenium(III)–polypyridyl complex; Kinetic study; Electron transfer reaction; Marcus theory
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Electron transfer reactions of methionine peptides with photochemically generated ruthenium(III)–polypyridyl complexes
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 295, 1 December 2014, Pages 70–78
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us