Figure 8.

Modifications of tyrosine observed after treatment using control oxidants. Peroxynitrite was most efficient, with higher pH boosting the introduction of multiple groups. Labels: +Y (tyrosyl, +180.066 Da), +OH (hydroxyl, +15.9949 Da), +NO (nitroso, +28.9902 Da), and +NO₂ (nitro, +44.9851 Da). Up to four groups were observed per molecule (indicated by light to dark grey). The introduction of diverse groups is represented as “mixed” (Compounds 20 to 27, Table 1). Treatment time 3 min, 0.3 mM tyrosine in 5 mM ammonium formate, pH 7.4, direct infusion high-resolution mass spectrometry (MS). Relative compound intensities are given (tyrosine ~4948 counts in control).