FIGURE 17.
A, the proposed mechanism of tryptophan hydroperoxide formation in the presence of co-generated •NO and O2⨪ fluxes. B, MRM chromatograms of TrpOOH (237.1 → 146.0) for the incubation mixture containing PAPA-NONOate (104 μm; •NO flux = 1 μm/min), xanthine oxidase (25 milliunits/ml; O2⨪ flux = 2 μm/min), hypoxanthine (1 mm), tryptophan (1 mm), catalase (100 units/ml), DTPA (100 μm), and phosphate buffer (50 mm), obtained by LC/MS after the indicated time of incubation. After 1 h, allopurinol and then CBA were added (100 μm). C, same as B, but the MRM chromatograms of TrpOH (221.1 → 175.0) are shown.