Stern J O, Peisach E, Peisach J, Blumberg W E, Lu A Y, Ryan W D, Levin W, West S
Adv Exp Med Biol. 1975;58(00):189-202. doi: 10.1007/978-1-4615-9026-2_13.
The time course of infuction of rat liver microsomal cytochrome P-450 by the polycyclic hydrocarbon 3-methylcholanthrene was followed by measuring the specific content of cytochrome P-450, benzpyrene hydroxylase activity, and the percent of cytochrome P-450 existing as the high-spin form (g equal to 7.9, 3.7 and 1.7) as determined by low temperature EPR spectroscopy. Significant increases in benzpyrene hydroxylase, cytochrome P-450 and high-spin ferric hemoprotein are seen twenty-four hours following 3-methylcholanthrene treatment. Administration of DL-ethionine prior to 3-methylcholanthrene treatment effectively blocks any increase in benzypyrene hydroxylase and cytochrome P-450 but not the increase in the levels of the high-spin species of the hemoprotein normally seen following 3-methylcholanthrene induction. In addition, partially purified cytochrome P-450 can be isolated from liver microsomes of 3-methylcholanthrene treated rats as low-spin ferric hemoprotein containing essentially no high-spin species (smaller than 1 per cent). This partially purified hemoprotein has the same substrate specificity as the microsomes from which it was derived. It is therefore concluded that the appearance of the high-spin form of cytochrome P-450, as quantitated by EPR, does not correlate with the induction of cytochrome P-450 and benezpyrene hydroxylase activity by 3-methylcholanthrene.
通过测量细胞色素P - 450的比含量、苯并芘羟化酶活性以及低温电子顺磁共振光谱法测定的作为高自旋形式（g等于7.9、3.7和1.7）存在的细胞色素P - 450的百分比，跟踪多环烃3 - 甲基胆蒽诱导大鼠肝脏微粒体细胞色素P - 450的时间进程。在3 - 甲基胆蒽处理后24小时，观察到苯并芘羟化酶、细胞色素P - 450和高自旋铁血红蛋白显著增加。在3 - 甲基胆蒽处理之前给予DL - 乙硫氨酸可有效阻断苯并芘羟化酶和细胞色素P - 450的任何增加，但不能阻断通常在3 - 甲基胆蒽诱导后出现的血红蛋白高自旋物种水平的增加。此外，可以从3 - 甲基胆蒽处理的大鼠肝脏微粒体中分离出部分纯化的细胞色素P - 450，其为低自旋铁血红蛋白，基本上不包含高自旋物种（小于1%）。这种部分纯化的血红蛋白与它所来源的微粒体具有相同的底物特异性。因此得出结论，通过电子顺磁共振定量的细胞色素P - 450高自旋形式的出现与3 - 甲基胆蒽诱导细胞色素P - 450和苯并芘羟化酶活性无关。
