6-Nitrotryptophan: A Specific Reaction Product Of Tryptophan Residue In Human Cu, Zn-Sod Treated With Peroxynitrite
Human Cu,Zn-superoxide dismutase (SOD) was treated with peroxynitrite. The modified enzyme was digested by trypsin. Decrease of one peptide and appearance of three new peptides (A, B, C) with increase molecular weights of 16, 16, and 45 compared to that of the decreased peptide, respectively, were observed by LC/MS analysis. These increased molecular weights correspond to the addition of one oxygen and nitro group, respectively. Among these new peptides, the peptide C showed thesame visible absorption spectrum as that of 6-nitrotryptophan. We conclude 6-nitrotryptophan is one of the reaction products between tryptophan residue in Cu, Zn-SOD and peroxynitrite.
KeywordsNitric Oxide Nitro Group Tryptic Peptide Tryptophan Residue Ammonium Bicarbonate
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