Electron paramagnetic resonance studies on hepatic microsomal cytochrome P-450 from a marine teleost fish

Hepatic microsomal cytochrome P-450 from fish (Stenotomus versicolor), untreated or treated with 3-methylcholanthrene, 5, 6-benzoflavone, or tricaine methanesulfonate, exhibited an absorption maximum at 450 nm when reduced and ligated to CO. Microsomes from all groups exhibited EPR spectra with g values near 2.4, 2.24 and 1.9, yielding crystal field parameters similar to those for cytochrome P-450 from a variety of other sources. Treatment with 3-methylcholanthrene or 5, 6-benzoflavone resulted in elevated levels of aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity yet produced no apparent change in the levels or optical properties of CO-ligated cytochrome P-450. Tricaine methanesulfonate, a common fish anaesthetic, caused a decrease in the levels of fish cytochrome P-450.