Mechanisms of peroxynitrite-mediated nitration of tyrosine.
The mechanisms of tyrosine nitration by peroxynitrous acid or nitrosoperoxycarbonate were investigated with the CBS-QB3 method. Either the protonation of peroxynitrite or a reaction with carbon dioxide gives a reactive peroxide intermediate. Peroxynitrous acid-mediated nitration of phenol occurs via unimolecular decomposition to give nitrogen dioxide and hydroxyl radicals. Nitrosoperoxycarbonate also undergoes unimolecular decomposition to give carbonate and nitrogen dioxide radicals. The reactions of tyrosine with the hydroxyl or carbonate radicals give a phenoxy radical intermediate. The reaction of the nitrogen dioxide with this radical intermediate followed by tautomerization gives nitrated tyrosine in both cases. According to CBS-QB3 calculations, the rate-limiting step for the nitration of phenol is the decomposition of peroxynitrous acid or nitrosoperoxycarbonate.
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Hakan
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Gunaydin
K N
KN
Houk
D002245:Carbon Dioxide / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry; D030421:Peroxynitrous Acid / Q000737:chemistry*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism
D002254:Carbonates; D009566:Nitrates; C512272:nitrosoperoxycarbonate; D002245:Carbon Dioxide; D030421:Peroxynitrous Acid; D017665:Hydroxyl Radical; C002744:3-nitrotyrosine; D014443:Tyrosine; D009585:Nitrogen Dioxide