Optical and Electron Paramagnetic Resonance Studies of Partially Purified Rabbit Liver Cytochrome P-450
Hildebrandt, Remmer and Estabrook (1968) studied the “off-balance” spectrum of oxidized cytochrome P-450 from rabbit liver microsomes by comparing microsomes from either phénobarbital (PB) or 3-methylcholanthrene (MC) treated animals in the sample cuvette with microsomes from control animals in the reference cuvette. By using the technique of Kinoshita and Horie (1967) in which the concentrations of cytochrome b5 are equalized in both cuvettes, they were able to observe the “absolute spectrum” of the cytochrome P-450 as the difference in absorption between the two cuvettes. When hexobarbital was added to the sample cuvette containing microsomes from a polycyclic aromatic hydrocarbon-induced animal, the spectrum took on the features of hepatic microsomal cytochrome P-450 from a PB induced animal. By analogy with work on other heme proteins (George, Bettlestone and Griffith, 1961) it appeared that the change in spectrum was characteristic of a change in spin state from the high spin form predominantly observed in the polycyclic aromatic hydrocarbon-induced cytochrome to the low spin form seen in the phEnobarbital induced type.
KeywordsHigh Spin High Spin State Heme Protein Sample Cuvette Reference Cuvette
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