N-15-CIDNP investigations during tryptophan, N-acetyl-L-tryptophan, and melatonin nitration with reactive nitrogen species

作者：Lehnig M^*; Kirsch M

来源：Free Radical Research, 2007, 41(5): 523-535.

DOI：10.1080/10715760601161445

• tryptophan
• 6-nitrotryptophan
• melatonin
• peroxynitrite
• reactive nitrogen species (RNS)
• nitrogen dioxide

Tryptophan and melatonin are nitrated by peroxynitrite; tryptophan residues in proteins are susceptible to attack by reactive nitrogen species. Nitrated tryptophan might therefore be used as a biomarker for the involvement of reactive species derived from nitrogen oxide in a variety of pathophysiological conditions. The radical character of the tryptophan (Trp) and N-acetyl-L- tryptophan (N-AcTrp) nitration with peroxynitrite is shown using N-15-CIDNP. During the decay of peroxynitrite-N-15 in the presence of Trp at pH 5 in the probe of a N-15-NMR spectrometer, the N-15-NMR signals of various nitrated tryptophans ((NO2)-N-15-Trp) show emission (E). The effects are built up in radical pairs [Trp(.), (NO2.)-N-15](F) formed by diffusive encounters of radicals (NO2.)-N-15 and Trp(.) generated during decay of peroxynitrite-N-15 in the presence of Trp. Similar N-15-CIDNP effects are observed during reaction of Trp and/or N-AcTrp using the nitrating systems (HNO3)-N-15, (HNO4)-N-15 and H2O2/(NO2-)-N-15/HRP, which are also built up in radical pairs [Trp(.), (NO2.)-N-15](F). During nitration of melatonin (Mel) with peroxynitrite-N-15 and (HNO4)-N-15, the N-15-NMR signal of 4-nitromelatonin (4-O-15(2)-Mel) shows emission arising from radical pairs [Mel(.), (NO2.)-N-15](F) which are formed in an analogous manner.

• 出版日期2007