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Light-induced reduction of bovine adrenodoxin via the covalently bound ruthenium(II) bipyridyl complex: Intramolecular electron transfer and crystal structure

Item Type:Article
Title:Light-induced reduction of bovine adrenodoxin via the covalently bound ruthenium(II) bipyridyl complex: Intramolecular electron transfer and crystal structure
Creators Name:Halavaty, A. and Mueller, J.J. and Contzen, J. and Jung, C. and Hannemann, F. and Bernhardt, R. and Galander, M. and Lendzian, F. and Heinemann, U.
Abstract:Bovine adrenodoxin (Adx) plays an important role in the electron-transfer process in the mitochondrial steroid hydroxylase system of the bovine adrenal cortex. Using electron paramagnetic resonance (EPR) spectroscopy, we showed that photoreduction of the [2Fe-2S] cluster of Adx via (4'-methyl-2,2'-bipyridine)bis(2,2'-bipyridine)ruthenium(II) [Ru(bpy)2(mbpy)] covalently attached to the protein surface can be used as a new approach to probe the "shuttle" hypothesis for the electron transfer by Adx. The 1.5 A resolution crystal structure of a 1:1 Ru(bpy)2(mbpy)-Adx(1-108) complex reveals the site of modification, Cys95, and allows to predict the possible intramolecular electron-transfer pathways within the complex. Photoreduction of uncoupled Adx, mutant Adx(1-108), and Ru(bpy)2(mbpy)-Adx(1-108) using safranin T as the mediating electron donor suggests that two electrons are transferred from the dye to Adx. The intramolecular photoreduction rate constant for the ruthenated Adx has been determined and is discussed according to the predicted pathways.
Keywords:2,2'-Dipyridyl, Adrenodoxin, Competitive Binding, X-Ray Crystallography, Electron Spin Resonance Spectroscopy, Electron Spin Resonance Spectroscopy, Kinetics, Light, Molecular Models, Oxidation-Reduction, Protein Conformation, Ruthenium, Animals, Cattle
Source:Biochemistry
ISSN:0006-2960
Publisher:American Chemical Society (U.S.A.)
Volume:45
Number:3
Page Range:709-718
Date:24 January 2006
Official Publication:https://doi.org/10.1021/bi0510330
PubMed:View item in PubMed

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