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; g_x = 2.00814; g_y = 2.00433; g_z = 2.00218; individual linewidth components, DH_x = 4.54 G; DH_y = 3.16 G; DH_z = 3.12 G; hyperfine splitting constants (all in MHz) and Euler angles (degree):

Ab1x = 24.34;	Ab1y = 20.83;	Ab1z = 20.83;	fb1 = 0o;
Ab2x = 12.36;	Ab2y = 7.73;	Ab2z = 7.73;	fb2 = 0o;
AC3x = -25.6;	AC3y = -8.0;	AC3z = -19.1;	fC3 = 22o;
AC5x = -27.5;	AC5y = -8.0;	AC5z = -20.5;	fC5 = -22o;
AC2x = 5.0;	AC2y = 7.5;	AC2z = 1.5;	fC2 = 10o;
AC6x = 5.0;	AC6y = 7.5;	AC6z = 1.5;	fC6 = -10o.