Fig. 2.

Top panel: UV-vis spectra of ferric myoglobin (100 µM) in the presence of varying amounts of nitrite, in 50 mM phosphate pH 7.4, room temperature; shown as inset is a binding curve whose theoretical fit indicates a binding constant of 14 mM. Bottom panel: EPR spectra of Mb in the presence and absence of nitrite, at 10 K. The g-values of the signals are indicated. Instrument conditions: microwave frequency 9.47 GHz, microwave power 3.18 mW, modulation frequency 100 kHz, modulation amplitude 5 G, sweep rated 22.6 G/s; time constant 81.92 ms, single sweep for each spectrum.