Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases

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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.

Original languageEnglish
Pages (from-to)433-444
Number of pages12
JournalJBIC Journal of Biological Inorganic Chemistry
Volume11
Issue number4
DOIs
Publication statusPublished - 1 Jun 2006

Keywords

  • Electron transfer
  • Iron-sulfur protein
  • Oxidative stress
  • Rubredoxin
  • Superoxide reductase

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