Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals
| Autor: | Eduardo Silva, Camilo López-Alarcón, Eduardo Pino, Eva Dorta, Hernán Speisky, Eduardo Fuentes-Lemus, Michael J. Davies, E. Lissi, Elizabeth Sánchez Escobar, M. L. Abasq, Alexis Aspée |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
chemistry.chemical_classification Super oxide dismutase Chemistry Stereochemistry General Chemical Engineering Radical Tryptophan Peptide General Chemistry Reaction intermediate Human serum albumin Amino acid 03 medical and health sciences chemistry.chemical_compound 030104 developmental biology medicine Lysozyme medicine.drug |
| Zdroj: | RSC Advances. 6:57948-57955 |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c6ra12859a |
| Popis: | The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROO˙), follows a complex mechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towards ROO˙ should be strongly affected by its inclusion in peptides and proteins. To examine the latter, we investigated (by fluorescence) the kinetic of the consumption of free, peptide- and protein-Trp residues towards AAPH (2,2′-azobis(2-amidinopropane)dihydrochloride)-derived free radicals. Interestingly, the initial consumption rates (Ri) were only slightly influenced by the inclusion of Trp in small peptides and proteins (human serum albumin and human superoxide dismutase). Depending on the Trp concentration, the Riversus Trp concentration ([Trp]) plots showed three regions. At low Trp concentrations (1–10 μM), a linear dependence was observed between Ri and [Trp]; at intermediate Trp concentrations (10–50 μM), the values of Ri were nearly constant; and at high Trp concentrations (50 μM to 1 mM), a slower increase of Ri than expected for chain reactions. Similar behavior was detected for all three systems (free Trp, and Trp in peptides and proteins). For the first time we are showing that alkoxyl radicals, formed from self-reaction of ROO˙, are responsible of the Trp oxidation at low concentrations, while at high Trp concentrations, a mixture of peroxyl and alkoxyl radicals are involved in the oxidation of Trp residues. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|