Radiation chemical studies of Gly-Met-Gly in aqueous solution.
Important biological consequences are related to the reaction of HO•radicals with methionine (Met). Several fundamental aspects remain to be defined when Met is an amino acid residue incorporated in the interior of peptides and proteins. The present study focuses on Gly-Met-Gly, the simplest peptide where Met is not a terminal residue. The reactions of HO•with Gly-Met-Gly and its N-acetyl derivative were studied by pulse radiolysis technique. The transient absorption spectra were resolved into contributions from specific components of radical intermediates. Moreover, a detailed product analysis is provided for the first time for Met-containing peptides in radiolytic studies to support the mechanistic proposal. By parallel radiolytical and electrochemical reactions and consequent product identification, the formation of sulfoxide attributed to the direct HO•radical attack on the sulfide functionality of the Met residue could be excluded, with the in situ generated hydrogen peroxide responsible for this oxidation. LC-MS and high resolution MS/MS were powerful analytical tools to envisage the structures of five products, thus allowing to complete the mechanistic picture of the overall Met-containing peptide reactivity.
a ISOF , Consiglio Nazionale delle Ricerche , Bologna , Italy.
Sebastian
S
Barata-Vallejo
a ISOF , Consiglio Nazionale delle Ricerche , Bologna , Italy.
Carla
C
Ferreri
b Department of Pharmacy , University of Groningen , Groningen , The Netherlands.
Tao
T
Zhang
b Department of Pharmacy , University of Groningen , Groningen , The Netherlands.
Hjalmar
H
Permentier
b Department of Pharmacy , University of Groningen , Groningen , The Netherlands.
Rainer
R
Bischoff
c Radiation Laboratory , University of Notre Dame , Notre Dame , IN , USA.
Krzysztof
K
Bobrowski
a ISOF , Consiglio Nazionale delle Ricerche , Bologna , Italy.|d Institute of Nanoscience and Nanotechnology , NCSR Demokritos , Athens , Greece.
Chryssostomos
C
Chatgilialoglu
D005609:Free Radicals / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry*; D010084:Oxidation-Reduction; D011839:Radiation, Ionizing
D005609:Free Radicals; D008715:Methionine
EC-MS; LC–MS/MS; Methionine; electrochemistry; free radicals; ionizing radiation; peptide; reaction mechanism