EPR-spectroscopy of reduced oxyferrous-P450cam

X-irradiation of the ternary complex of P450:substrate:O2 at 77 K produces a reduced intermediate by electron addition to the Fe:O2 complex which can be studied by EPR-spectroscopy. The EPR spectrum of the new species exhibits rhombic symmetry with g-factors of 2.27, 2.17 and 1.95, respectively. Increasing the temperature of the sample to 190 K results in loss of intensity of the intermediate signals. X-irradiation of oxymyo- and oxyhemoglobin produces similar EPR signals indicating that the added electron is resident on the Fe:O2 compleX (Kappl, R., et al. (1985) Biochim. Biophys. Acta 870, 20-30).