Taurine bromamine: A potent oxidant of tryptophan residues in albumin
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Data
2011-03-15
Autores
Ximenes, Valdecir Farias [UNESP]
da Fonseca, Luiz Marcos [UNESP]
de Almeida, Ana Carolina [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Resumo
Taurine is the most abundant free amino acid in leukocytes and can react with HOBr to produce taurine bromamine (Tau-NHBr). The aim of this study was to assess the ability of Tau-NHBr to oxidize tryptophan, either free or as a residue in albumin. We have demonstrated that Tau-NHBr is a powerful oxidant for tryptophan. Importantly, in comparison to taurine chloramine, HOCl or HOBr, Tau-NHBr exhibits a degree of selectivity for tryptophan. Oxidation of albumin by Tau-NHBr resulted in emission of light, and the quantum yield was more than 10-fold more efficient than that of the other oxidants. The fluorescence band corresponding to oxidized albumin (lambda(ex) 350/lambda(em) 450), which is characteristic of the formation of formylkynurenine, was significantly higher in reactions using Tau-NHBr. Excitation of the fluorescent probe 8-anilino-1-naphthalenesulfonate at 295 nm was used to assess the depletion of tryptophan residues in albumin. Results from this experiment further supported a higher efficiency of oxidation of tryptophan residues by Tau-NHBr. Other parameters of protein oxidation, including cysteine depletion and formation of carbonyl groups, were not significantly different between the oxidants tested. In conclusion, these results indicate that Tau-NHBr has a higher affinity for tryptophan residues in proteins. (C) 2010 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
Tryptophan, Taurine chloramine, Taurine bromamine, Hypochlorous acid, Hypobromous acid, Albumin
Como citar
Archives of Biochemistry and Biophysics. New York: Elsevier B.V., v. 507, n. 2, p. 315-322, 2011.