Abstract
I would like to mention three observations which may have some bearing on the interpretation of the inverse Type I spectrum observed by Dr. Witmer: 1) of the five or six Type I compounds we have employed, only hexobarbital gives an inverse Type I spectrum with microsomes from 3-methylcholanthrene-treated rats; 2) solubilized and purified (about 4-fold) cytochrome P1-450 (P-448) obtained by Dr. Fujita (Fujita, Shoeman and Mannering, J. Biol. Chem., 248, 2192, 1973) in my laboratory gave neither a Type I nor an inverse Type I spectrum with hexobarbital; 3) Dr. Lu and associates observed that purified cytochromes P-450 and P1-450 give about the same amount of high spin signal and that this represents only a small amount of the P-450 hemoprotein—about 5%, if I remember correctly. This suggests that the high spin signal observed with membrane bound P-450 hemoproteins may be imparted by membrane components associated with the hemoproteins. During their purification, the P-450 hemoproteins lost their high spin characteristic because they are no longer associated with the membrane components responsible for the high spin signal.
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© 1975 Plenum Press, New York
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Cooper, D.Y., Rosenthal, O., Snyder, R., Witmer, C. (1975). General Discussion. In: Cooper, D.Y., Rosenthal, O., Snyder, R., Witmer, C. (eds) Cytochromes P-450 and b5. Advances in Experimental Medicine and Biology, vol 58. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-9026-2_16
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DOI: https://doi.org/10.1007/978-1-4615-9026-2_16
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