A. Complete room temperature incubation containing porcine NADPH – cytochrome P450 reductase (0.016 μM), 2.4 mM NADPH, 4.0 mM sulfur mustard, 1.03 M 4-POBN and 0.21 mM cytochrome c in 0.1M KPO4 buffer containing 0.25 M NaCl, pH 7.5. B. Same as in A, but with the porcine reductase replaced with an equal volume of buffer. C. Same as A, but without the NADPH. D. Same as A, but without sulfur mustard. These spectra were recorded on a Bruker ESP 300E spectrometer equipped with a 4103 TM cavity operating at 9.80 GHz, microwave power: 10 mW, sweep width: 100 Gauss, midscale: approximately 3488 G, number of scans: 3, receiver gain: 1.25e5, time constant: 327 ms, conversion time: 655 ms, modulation amplitude: 1.0 G. All spectra are presented at the same gain. The 10 Gauss bar is included to define the scale.