OXIDATIVE MODIFICATION OF TRYPTOPHAN RESIDUES EXPOSED TO PEROXYNITRITE

The aim of this study was to clarify the mechanism of loss of Trp resi dues in proteins exposed to peroxynitrite. The Trp residues in bovine serum albumin and collagen IV were decreased by peroxynitrite treatmen t. To identify the degradation products of the Trp residue by peroxyni trite, tert-butoxycarbonyl-L-tryptophan (Boc-Trp) was used as a model of the Trp residue in proteins, and the products formed from peroxynit rite-treated Boc-Trp were then isolated. Boc-Trp decreased with an inc rease in peroxynitrite concentration. N-Formylkynurenine, oxindole, an d hydropyrroloindole were identified as major products. The formation of these products may account for the losses of Trp residues in protei ns by peroxynitrite. (C) 1997 Academic Press.