Fig. 3. A - an EPR spectrum of the reaction mixture of 0.71 mM (by haem) metHbA and 7.1 mM H2O2 taken at room temperature, pH 8 (aerated condition), immediately after mixing (the middle of the spectrum corresponds to ~6 s of reaction time). The instrumental conditions were: microwave frequency, 9.798 GHz; microwave power, 1.27 mW; modulation amplitude, 2 G; time constant, 10.2 ms, sweep time, 10.5 sec; central field, 3490 G; single scan.
B - a computer simulated spectrum performed with the software simpow6 (Mark Nilges, Illinois EPR Research Center, http://ierc.scs.uiuc.edu/~nilges/software.html). The simulation parameters were as follows: microwave frequency, 9.79747 GHz; central field, 3482.25 G; field width, 80 G; modulation amplitude, 2.00 G; gx = 2.00814; gy = 2.00433; gz = 2.00218; individual linewidth components, DHx = 4.54 G; DHy = 3.16 G; DHz = 3.12 G; hyperfine splitting constants (all in MHz) and Euler angles (degree):
Ab1x = 24.34; Ab1y = 20.83; Ab1z = 20.83; fb1 = 0;
Ab2x = 12.36; Ab2y = 7.73; Ab2z = 7.73; fb2 = 0;
AC3x = -25.6; AC3y = -8.0; AC3z = -19.1; fC3 = 22;
AC5x = -27.5; AC5y = -8.0; AC5z = -20.5; fC5 = -22;
AC2x = 5.0; AC2y = 7.5; AC2z = 1.5; fC2 = 10;
AC6x = 5.0; AC6y = 7.5; AC6z = 1.5; fC6 = -10.