IMMUNOQUANTIFICATION OF EPOXIDE HYDROLASE AND CYTOCHROME-P-450 ISOZYMES IN FETAL AND ADULT HUMAN-LIVER MICROSOMES
IMMUNOQUANTIFICATION OF EPOXIDE HYDROLASE AND CYTOCHROME-P-450 ISOZYMES IN FETAL AND ADULT HUMAN-LIVER MICROSOMES
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DOI：
10.1111/j.1432-1033.1985.tb09107.x
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发表时间：
1985-01-01
期刊：
影响因子：
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通讯作者：
LEROUX, JP
中科院分区：
文献类型：
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作者：
CRESTEIL, T;BEAUNE, P;LEROUX, JP
用免疫化学方法测定了成人和胎儿肝脏的环氧化物水解酶和3种细胞色素P-450同工酶，并初步确定了它们与某些酶活性的相关性。成人肝脏P-450同工酶5、8、9与细胞色素P-450浓度无显著正相关。在胎儿肝微粒体中，同工酶8不能通过电泳或免疫化学方法检测到。同工酶5是胎儿肝脏中主要的同工酶，其浓度的升高与总P-450水平密切相关。如前所述，成人肝脏芳烃羟化酶活性与同工酶8的浓度有关。在胎儿制剂中，同工酶8的缺失与非常低的芳烃羟化酶活性有关。奥尔德林环氧化酶和苯丙胺- n -去甲基化酶活性与同工酶5浓度相关，但对成人和胎儿微粒体具有不同的斜率，成人制剂对这两种反应的催化效率更高。相反，脱氢表雄酮16。与同工酶5浓度相关的-羟化酶在胎儿微粒体中比在成人微粒体中更活跃。此外，如果成人样品中乙酰苯胺羟化酶随着同工酶5浓度的增加而增加，则胎儿微粒体中乙酰苯胺羟化酶的活性与P-450同工酶的水平没有相关性。位置11和12的月桂酸羟基化以及位置16的脱氢表雄酮羟基化。随P-450总浓度的增加而增加，但与同工酶浓度无关。最后，环氧化物水解酶对苯并芘4,5-氧化物的活性与其免疫化学测定的水平密切相关。这些结果清楚地表明，多种机制参与了人类胎儿不同药物代谢酶的调节。
Epoxide hydrolase and three cytochrome P-450 isozymes were immunochemically determined in microscomes from adult and fetal human liver and tentatively correlated with some enzyme activities. The P-450 isozymes 5, 8 and 9 present in adult liver could not be positively correlated with the total cytochrome P-450 concentration spectrophotometrically determined. In fetal liver microsomes, isozyme 8 could not be detected by either electrophretic or immunochemical procedures. Isozyme 5 was the major isozyme present in the fetal liver and its concentration increased in close relation with the total P-450 level. As shown previously, arylhydrocarbon hydroxylase activity was related to the concentration of isozyme 8 in adult liver. In fetal preparations, the absence of isozyme 8 was associated with a very low arylhydrocarbon hydroxylase activity. Aldrin epoxidase and benzphetamine-N-demethylase activities were correlated with isozyme 5 concentration, but with different slopes for adult and fetal microsomes: adult preparations catalyzed these two reactions more efficiently. Conversely, the dehydroepiandrosterone 16.beta.-hydroxylase, also associated with isozyme 5 concentration, was more active in fetal than in adult microsomes. Moreover, if acetanilide hydroxylase increased with isozyme 5 concentration in adult samples, no correlation occurred between activity and P-450 isozyme level in fetal microsomes. Hydroxylations of lauric acid in positions 11 and 12 and of dehydroepiandrosterone in position 16.alpha. increased with total P-450 concentration but not with isozyme concentrations whatever the age considered. Lastly, epoxide hydrolase activity towards benzopyrene 4,5-oxide was closely associated with its immunochemically determined level. These results clearly suggest that multiple mechanisms are involved in the regulation of different drug-metabolizing enzymes in the human fetus.