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Aromatic hydroxylation and nitration of phenylalanine and tyrosine by peroxynitrite
Author(s) -
van der Vliet Albert,
O'Neill Charles A.,
Halliwell Barry,
Cross Carroll E.,
Kaur Harparkash
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80391-9
Subject(s) - peroxynitrite , nitration , chemistry , radical , hydroxylation , phenylalanine , peroxynitrous acid , hydroxyl radical , tyrosine , photochemistry , electrophilic aromatic substitution , protonation , superoxide , aromatic amino acids , tetranitromethane , organic chemistry , biochemistry , amino acid , enzyme , ion
Peroxynitrite is a highly reactive species, generated from Superoxide and nitric oxide. Some effects of peroxynitrite are ascribed to the molecule itself, but decomposition products of the protonated form, peroxynitrous acid, may account for much of its reactivity in biological systems. Suggested products include highly‐reactive hydroxyl radicals, but thermodynamic calculations have been used to claim that free hydroxyl radicals cannot be formed from peroxynitrite. We utilized aromatic hydroxylation of phenylalanine as a specific detector of hydroxyl radicals, and found that incubation of phenylalanine with peroxynitrite leads to a small amount of p ‐, m ‐ and o ‐tyrosine, specific products of attack by this radical. Products of nitration of phenylalanine and tyrosine were also detected, as was dityrosine. Peroxynitrite decomposition generates several reactive species, including some that can nitrate aromatic rings. Formation of nitro‐aromatic compounds may be a useful marker of peroxynitrite generation in biological systems.