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Reactions of yeast thioredoxin peroxidases I and II with hydrogen peroxide and peroxynitrite: rate constants by competitive kinetics.
Free Radic Biol Med. 2007 Feb 01; 42(3):326-34.FR

Abstract

Peroxiredoxins are receiving increasing attention as defenders against oxidative damage and sensors of hydrogen peroxide-mediated signaling events. Likely to be critical for both functions is a rapid reaction with hydrogen peroxide, typically with second-order rate constants higher than 10(5) M(-1) s(-1). Until recently, however, the values reported for these rate constants have been in the range of 10(4)-10(5) M(-1) s(-1), including those for cytosolic thioredoxin peroxidases I (Tsa1) and II (Tsa2) from Saccharomyces cerevisiae. To resolve this apparent paradox, we developed a competitive kinetic approach with horseradish peroxidase to determine the second-order rate constant of the reaction of peroxiredoxins with peroxynitrite and hydrogen peroxide. This method was validated and allowed for the determination of the second-order rate constant of the reaction of Tsa1 and Tsa2 with peroxynitrite (k approximately 10(5) M(-1) s(-1)) and hydrogen peroxide (k approximately 10(7) M(-1) s(-1)) at pH 7.4, 25 degrees C. It also permitted the determination of the pKa of the peroxidatic cysteine of Tsa1 and Tsa2 (Cys47) as 5.4 and 6.3, respectively. In addition to providing a useful method for studying thiol protein kinetics, our studies add to recent reports challenging the popular belief that peroxiredoxins are poor enzymes toward hydrogen peroxide, as compared with heme and selenium proteins.

Authors+Show Affiliations

Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17210445

Citation

Ogusucu, Renata, et al. "Reactions of Yeast Thioredoxin Peroxidases I and II With Hydrogen Peroxide and Peroxynitrite: Rate Constants By Competitive Kinetics." Free Radical Biology & Medicine, vol. 42, no. 3, 2007, pp. 326-34.
Ogusucu R, Rettori D, Munhoz DC, et al. Reactions of yeast thioredoxin peroxidases I and II with hydrogen peroxide and peroxynitrite: rate constants by competitive kinetics. Free Radic Biol Med. 2007;42(3):326-34.
Ogusucu, R., Rettori, D., Munhoz, D. C., Netto, L. E., & Augusto, O. (2007). Reactions of yeast thioredoxin peroxidases I and II with hydrogen peroxide and peroxynitrite: rate constants by competitive kinetics. Free Radical Biology & Medicine, 42(3), 326-34.
Ogusucu R, et al. Reactions of Yeast Thioredoxin Peroxidases I and II With Hydrogen Peroxide and Peroxynitrite: Rate Constants By Competitive Kinetics. Free Radic Biol Med. 2007 Feb 1;42(3):326-34. PubMed PMID: 17210445.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Reactions of yeast thioredoxin peroxidases I and II with hydrogen peroxide and peroxynitrite: rate constants by competitive kinetics. AU - Ogusucu,Renata, AU - Rettori,Daniel, AU - Munhoz,Daniela Cristina, AU - Netto,Luis Eduardo Soares, AU - Augusto,Ohara, Y1 - 2006/10/20/ PY - 2006/07/20/received PY - 2006/09/28/revised PY - 2006/10/14/accepted PY - 2007/1/11/pubmed PY - 2007/3/14/medline PY - 2007/1/11/entrez SP - 326 EP - 34 JF - Free radical biology & medicine JO - Free Radic Biol Med VL - 42 IS - 3 N2 - Peroxiredoxins are receiving increasing attention as defenders against oxidative damage and sensors of hydrogen peroxide-mediated signaling events. Likely to be critical for both functions is a rapid reaction with hydrogen peroxide, typically with second-order rate constants higher than 10(5) M(-1) s(-1). Until recently, however, the values reported for these rate constants have been in the range of 10(4)-10(5) M(-1) s(-1), including those for cytosolic thioredoxin peroxidases I (Tsa1) and II (Tsa2) from Saccharomyces cerevisiae. To resolve this apparent paradox, we developed a competitive kinetic approach with horseradish peroxidase to determine the second-order rate constant of the reaction of peroxiredoxins with peroxynitrite and hydrogen peroxide. This method was validated and allowed for the determination of the second-order rate constant of the reaction of Tsa1 and Tsa2 with peroxynitrite (k approximately 10(5) M(-1) s(-1)) and hydrogen peroxide (k approximately 10(7) M(-1) s(-1)) at pH 7.4, 25 degrees C. It also permitted the determination of the pKa of the peroxidatic cysteine of Tsa1 and Tsa2 (Cys47) as 5.4 and 6.3, respectively. In addition to providing a useful method for studying thiol protein kinetics, our studies add to recent reports challenging the popular belief that peroxiredoxins are poor enzymes toward hydrogen peroxide, as compared with heme and selenium proteins. SN - 0891-5849 UR - https://www.unboundmedicine.com/medline/citation/17210445/Reactions_of_yeast_thioredoxin_peroxidases_I_and_II_with_hydrogen_peroxide_and_peroxynitrite:_rate_constants_by_competitive_kinetics_ DB - PRIME DP - Unbound Medicine ER -