Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals
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Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals. / Fuentes-Lemus, E.; Dorta, E.; Escobar, E. ; Aspee, A. ; Pino, E.; Abasq, M.L. ; Speisky, H. ; Silva, E. ; Lissi, E. ; Davies, Michael Jonathan; Lopez-Alarcon, C.
In: RSC Advances, Vol. 6, No. 63, 2016, p. 57948-57955.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals
AU - Fuentes-Lemus, E.
AU - Dorta, E.
AU - Escobar, E.
AU - Aspee, A.
AU - Pino, E.
AU - Abasq, M.L.
AU - Speisky, H.
AU - Silva, E.
AU - Lissi, E.
AU - Davies, Michael Jonathan
AU - Lopez-Alarcon, C.
PY - 2016
Y1 - 2016
N2 - The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROOc), follows a complexmechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towardsROOc should be strongly affected by its inclusion in peptides and proteins. To examine the latter, weinvestigated (by fluorescence) the kinetic of the consumption of free, peptide- and protein-Trp residuestowards AAPH (2,20-azobis(2-amidinopropane)dihydrochloride)-derived free radicals. Interestingly, theinitial consumption rates (Ri) were only slightly influenced by the inclusion of Trp in small peptides andproteins (human serum albumin and human superoxide dismutase). Depending on the Trpconcentration, the Ri versus Trp concentration ([Trp]) plots showed three regions. At low Trpconcentrations (1–10 mM), a linear dependence was observed between Ri and [Trp]; at intermediate Trpconcentrations (10–50 mM), the values of Ri were nearly constant; and at high Trp concentrations (50 mMto 1 mM), a slower increase of Ri than expected for chain reactions. Similar behavior was detected for allthree systems (free Trp, and Trp in peptides and proteins). For the first time we are showing that alkoxylradicals, formed from self-reaction of ROOc, 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 oxidationof Trp residues.
AB - The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROOc), follows a complexmechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towardsROOc should be strongly affected by its inclusion in peptides and proteins. To examine the latter, weinvestigated (by fluorescence) the kinetic of the consumption of free, peptide- and protein-Trp residuestowards AAPH (2,20-azobis(2-amidinopropane)dihydrochloride)-derived free radicals. Interestingly, theinitial consumption rates (Ri) were only slightly influenced by the inclusion of Trp in small peptides andproteins (human serum albumin and human superoxide dismutase). Depending on the Trpconcentration, the Ri versus Trp concentration ([Trp]) plots showed three regions. At low Trpconcentrations (1–10 mM), a linear dependence was observed between Ri and [Trp]; at intermediate Trpconcentrations (10–50 mM), the values of Ri were nearly constant; and at high Trp concentrations (50 mMto 1 mM), a slower increase of Ri than expected for chain reactions. Similar behavior was detected for allthree systems (free Trp, and Trp in peptides and proteins). For the first time we are showing that alkoxylradicals, formed from self-reaction of ROOc, 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 oxidationof Trp residues.
U2 - 10.1039/C6RA12859A
DO - 10.1039/C6RA12859A
M3 - Journal article
VL - 6
SP - 57948
EP - 57955
JO - RSC Advances
JF - RSC Advances
SN - 2046-2069
IS - 63
ER -
ID: 164414087