Toward understanding the protein oxidation processes: ^•OH addition on tyrosine, phenylalanine, or methionine?

Abstract

Oxidation of peptides and proteins by OH radicals produced in oxidative stress or in radiotherapy, accidental irradiations, etc., is well known to form oxidative metabolites that are responsible for numerous diseases including neurodegenerative pathologies. Tyrosine (Tyr), Phenylalanine (Phe), and Methionine (Met) residues are known to be the major targets of OH radicals. This study aims at better understanding the OH addition process on these three amino acids. On the basis of different amino acid prototypes, the Gibbs energy (DG) (B3P86/6-31þG(d,p)) and rate constants (k TST ) (MPWB1K/6-31þG(d,p)) of OH addition were calculated. The OH addition capacity was studied (i) on the different positions of the aromatic rings of Tyr and Phe and (ii) on the S-atom of Met. The addition was favored on the aromatic rings of Tyr and Phe with almost the same DG addition values for both amino acids. No preferential position was found. The only parameter that may influence the OH-adduct formation is the presence or absence of intra-H bondings. In agreement with the experimental data available from the literature, the OH-adduct on Met appeared to be less favored.

Topological analyses of time-dependent electronic structures: application to electron-transfers in methionine enkephalin

“…This step could explain the nature of transients as well as the final compounds, but was too fast to be observed by pulse radiolysis. Several computational papers dealt with the oxidation of methionine and tyrosine [27,28].…”

Methionine one-electron oxidation: Coherent contributions from radiolysis, IRMPD spectroscopy, DFT calculations and electrochemistry

“…Details on the performance of our modified Bruker Esquire 3000+ were already published [14]. Different electron energies were used (40)(41)(42)(43)(44) We used the relatively small basis set 6-31G(d) (SB) and the greater basis set 6-311+G(2d,2p) (GB) considering the experimental and the theoretical difficulties linked to measurements of redox potentials.…”

“…We had previously performed preliminary theoretical approaches of the oxidation competition between Tyr and Met in isolated peptide models [43]. These first thermodynamic data indicated that Tyr •+ was more stable than Met •+ .…”

DFT and PM3 Computational Studies of the Reaction Mechanism of the Oxidation of L-Tyrosine by Iodine in the Gas Phase

“…Sci. Technol., 3(2): 106-116 August 2014 doi: 10.13170/AIJST.0302.06 111 considered (Laloo and Mahanti, 1990;Giulivi and Davies, 2001;Malika et al, 2010;Faller et al, 2002;Foppoli et al, 1997;Trouillas et al, 2011). Amino acids with aromatic side chain were oxidized more rapidly than the alkyl side chain amino acids.…”