title: The rate-limiting step of sulfiredoxin is associated with the transfer of the γ-phosphate of ATP to the sulfinic acid of overoxidized typical 2-Cys peroxiredoxins.
abstract: The eukaryotic sulfiredoxin (Srx) catalyzes the reduction of overoxidized typical 2-Cys peroxiredoxins PrxSO(2) via ATP/Mg(2+)-dependent phosphorylation of the sulfinic acid group, followed by formation of a PrxSO-SSrx thiolsulfinate intermediate. Using real-time kinetics of wild-type and C84A Srxs, and pH-rate profiles with ATP/Mg(2+) analogues, we show that the rate-limiting step of the reaction is associated with the chemical process of transfer of the γ-phosphate of ATP to the sulfinic acid, in contrast to that described by Jönsson et al. Two pK(apps) of 6.2 and 7.5 were extracted from the bell-shaped pH-rate profile, corresponding to the γ-phosphate of ATP, and to an acid-base catalyst, respectively.
authors.affiliation: Unité Mixte de Recherche CNRS-Université Henri Poincaré 7214 AREMS, Nancy Université, Faculté des Sciences et Technologies, Vandœuvre-lès-Nancy, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Roussel
authors.forename: Samia
authors.initials: S
authors.lastname: Boukhenouna
authors.forename: Sophie
authors.initials: S
authors.lastname: Rahuel-Clermont
authors.forename: Guy
authors.initials: G
authors.lastname: Branlant
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000465:Algorithms; D019943:Amino Acid Substitution; D055162:Biocatalysis; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics / Q000378:metabolism*; D054464:Peroxiredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013441:Sulfinic Acids / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013441:Sulfinic Acids; D000255:Adenosine Triphosphate; D054464:Peroxiredoxins; D050862:Oxidoreductases Acting on Sulfur Group Donors; C479426:SRX1 protein, S cerevisiae; D003545:Cysteine