Enzymatic Elimination of Hydrogen Peroxide by a Methemoglobin/L-Tyrosine System

Figures & data

Figure 1 (A) UV-vis spectra of 2 µM metHb and 2 µM ferrylHb just after isolation by GPC at 4°C. Inset is the migration (x4) of Q band region. (B) Difference of ESR spectra of the isolated ferrylHb in PBS (pH7.4) at 4 K and 25 K. (C) ESR chart of the isolated ferrylHb radical and ferrylHb radical in the presence of H₂O₂ remaining in the reaction mixture in PBS (pH7.4) at 25 K.

Figure 2 (A) Conversion of ferrylHb radical (2 µM) to metHb at 4°C (○) and 37°C (•) in PBS (pH7.4). (B) Conversion of ferrylHb radical (2 µM) to metHb in the presence of L-Tyr (500 µM) (•) and metHb in the absence of L-Tyr (○) at 4°C in PBS.

Figure 3 Time course of the changes in the ESR spectra of 113 µM ferrylHb radical mixed with (A) PBS (control) and (B) 900 µM L-Tyr.

Figure 4 Decrease in L-Tyr and a corresponding increase in diTyr is seen as the reaction of metHb with H₂O₂ proceeds at 37°C in presence of L-Tyr. The reaction mixture was sampled at the time intervals shown (0, 20, 40, and 60 min).