标题：Electron Paramagnetic Resonance Study of the High- and Low-Spin Forms of Cytochrome P-450 in Liver and in Liver Microsomes from a Methylcholanthrene-Treated Rabbit
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1970
卷号：67
期号：1
页码：172-179
DOI：10.1073/pnas.67.1.172
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The high- and low-spin forms of cytochrome P-450 were observed by electron paramagnetic resonance (epr) in a liver slice and in hepatic microsomes from a rabbit injected with methylcholanthrene. Quantitation of the epr absorption of these two chemical species and comparison with a preparation from a control rabbit showed that the single injection of drug increased the concentration of cytochrome P-450 to more than ten times its control value. Analysis of the epr spectrum for the high-spin compound showed that it is the most rhombically distorted ferric heme iron site yet observed (E/D = 0.10). It is suggested that microsomal cytochrome P-450 can exist in two interconvertible forms, in which the heme iron can either be high-spin or low-spin, depending upon the nature of the nonporphyrin ligands of the metal. There seems to be no need to postulate the existence of two different cytochrome P-450 proteins.
