Fig. S4.
The 9.39-GHz EPR spectra of 190-μM NOV1 and 190-μM NOV1-NO along with simulations of the S = 3/2 species observed with NOV1-NO. Spectra were collected at either 4 or 10 K with 10 G modulation amplitude and 0.05 mW power. (Trace A) Purified NOV1 at 10 K. (Trace B) EPR spectrum of NOV1 plus NO at 4 K. (Trace C) Simulation of an S = 3/2 iron center with g = 4.01, 3.98, and 2.00, and E/D = 0.002. The simulation was scaled to match the intensity of the experimental data shown in trace C. The temperature dependence and g values obtained from the simulations indicate that the signals arise from the ground state mS = 1/2 doublet of the S = 3/2 spin system.