Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases |
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Authors: | Françoise Auchère Sofia R Pauleta Pedro Tavares Isabel Moura José J G Moura |
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Institution: | (1) REQUIMTE—Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal;(2) Present address: Laboratoire d'Ingénierie des Protéines et Contrôle Métabolique, Dépt. de Biologie des Génomes, Institut Jacques Monod (UMR 7592 CNRS—Universités Paris 6 et 7), 2 Place Jussieu, 75251 Paris Cedex 05, France |
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Abstract: | In this work we present a kinetic study of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and members of the three different classes of superoxide reductases (SORs). SORs from the sulfate-reducing bacteria Desulfovibrio vulgaris (Dv) and D. gigas (Dg) were chosen as prototypes of classes I and II, respectively, while SOR from the syphilis spyrochete Treponema pallidum (Tp) was representative of class III. Our results show evidence for different behaviors of SORs toward electron acceptance, with a trend to specificity for the electron donor and acceptor from the same organism. Comparison of the different k
app values, 176.9±25.0 min−1 in the case of the Tp/Tp electron transfer, 31.8±3.6 min−1 for the Dg/Dg electron transfer, and 6.9±1.3 min−1 for Dv/Dv, could suggest an adaptation of the superoxide-mediated electron transfer efficiency to various environmental conditions. We also demonstrate that, in Dg, another iron–sulfur protein, a desulforedoxin, is able to transfer electrons to SOR more efficiently than rubredoxin, with a k
app value of 108.8±12.0 min−1, and was then assigned as the potential physiological electron donor in this organism.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. |
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Keywords: | Superoxide reductase Rubredoxin Oxidative stress Iron– sulfur protein Electron transfer |
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