Namkung M J, Chao S T, Juchau M R
Drug Metab Dispos. 1983 Jan-Feb;11(1):10-14.
Human placental mono-oxygenase activities were markedly increased after additions of micromolar quantities of hematin to reaction vessels. The magnitude of the increases diminished with increasing (induced) levels of hematin-independent activity. The activating effect of hematin could be observed in unbroken cell preparations, in whole homogenates, and in various subcellular fractions. Highest hematin-dependent activity was measured in microsomal fractions of placental homogenates. With benzo(a)pyrene as substrate, response to the stimulatory effect of hematin in human placental preparations was not as profound as that observed in monkey or rabbit placentas but was more marked than the responses observed in placental preparations from rats or mice. Hematin-activated mono-oxygenase activity present in washed microsomal fractions of human placental homogenates could be solubilized with detergents, the most effective of which was Triton N-101. The solubilized activity also could be partially purified by polyethylene glycol fractionation. Attempts to further purify, however, resulted in loss of activity. All results were consistent with the hypothesis that the effect of hematin is mediated via reconstitution of hematin-free apocytochrome(s) P-450.
向反应容器中添加微摩尔量的血晶素后，人胎盘单加氧酶活性显著增加。随着血晶素非依赖性活性水平的升高（诱导），增加的幅度减小。在完整细胞制剂、全匀浆和各种亚细胞组分中均可观察到血晶素的激活作用。在胎盘匀浆的微粒体组分中测得最高的血晶素依赖性活性。以苯并(a)芘为底物时，人胎盘制剂对血晶素刺激作用的反应不如在猴或兔胎盘中观察到的那样显著，但比在大鼠或小鼠胎盘制剂中观察到的反应更明显。人胎盘匀浆洗涤微粒体组分中存在的血晶素激活的单加氧酶活性可用去污剂溶解，其中最有效的是Triton N-101。溶解的活性也可通过聚乙二醇分级分离进行部分纯化。然而，进一步纯化的尝试导致活性丧失。所有结果均与血晶素的作用是通过无血晶素的脱辅基细胞色素P-450的重组介导的这一假设一致。
