OBLIGATORY ROLE OF CYTOCHROME-B5 IN THE MICROSOMAL METABOLISM OF METHOXYFLURANE
OBLIGATORY ROLE OF CYTOCHROME-B5 IN THE MICROSOMAL METABOLISM OF METHOXYFLURANE
复制标题
DOI：
10.1016/0006-2952(85)90307-7
复制
发表时间：
1985-01-01
影响因子：
5.8
通讯作者：
WASKELL, L
中科院分区：
文献类型：
--
作者：
CANOVADAVIS, E;CHIANG, JYL;WASKELL, L
细胞色素b5是挥发性麻醉剂甲氧氟烷代谢所需的复溶细胞色素P-450系统。为了确定复溶系统中的这一观察结果是否仅取决于各种组分的特定比例或某些其他偶然的未知因素，或者细胞色素b5是否在甲氧氟烷的肝微粒体代谢中发挥作用，进行了以下研究。在豚鼠体内产生了抗兔全细胞色素b5的抗体。细胞色素b5抗体能够抑制75%的甲氧氟烷微粒体代谢。该相同抗体还抑制复溶系统中的甲氧氟烷代谢。当细胞色素b5抗体在加入微粒体之前用纯化的细胞色素b5处理时，其不会抑制甲氧氟烷代谢。细胞色素b5抗体不抑制微粒体代谢的苄非他明。这表明甲氧氟烷的微粒体代谢需要细胞色素b5。细胞色素b5可能通过保留细胞色素P-450的特定构象而不是通过将第二个电子转移到细胞色素P-450来在甲氧氟烷的代谢中发挥作用。为了探索这种可能性，细胞色素b5与Mn 3-原卟啉IX重建。Mn 3-原卟啉IX衍生物保留了细胞色素b5的构象，但没有其电子转移特性。细胞色素b5的Mn衍生物不能刺激甲氧氟烷的代谢。细胞色素b5对甲氧氟烷的微粒体代谢是寡聚的，而对苄非他明的微粒体N-去甲基化则不是必需的。细胞色素b5的血红素部分在该反应中起着转移电子的作用。
Cytochrome b5 is required in the reconstituted cytochrome P-450 system for the metabolism of the volatile anesthetic methoxyflurane. To determine whether this observation in the reconstituted system was merely dependent on the particular ratios of the various components or some other fortuitous, unknown factor, or whether cytochrome b5 plays a role in the liver microsomal metabolism of methoxyflurane, the following studies were undertaken. Antibody to rabbit holocytochrome b5 was raised in guinea pigs. The antibody to cytochrome b5 was able to inhibit 75% of the microsomal metabolism of methoxyflurane. This same antibody also inhibited methoxyflurane metabolism in the reconstituted system. When the antibody to cytochrome b5 was treated with purified cytochrome b5 before addition to the microsomes, it did not inhibit methoxyflurane metabolism. The antibody to cytochrome b5 did not inhibit the microsomal metabolism of benzphetamine. This suggests that cytochrome b5 was required for the microsomal metabolism of methoxyflurane. It is possible that cytochrome b5 functioned in the metabolism of methoxyflurane by retaining a specific conformation of cytochrome P-450 and not by transferring the 2nd electron to cytochrome P-450. To explore this possibility, cytochrome b5 was reconstituted with Mn3--protoporphyrin IX. The Mn3--protoporphyrin IX derivative retained the conformation of cytochrome b5 but not its electron transfer properties. This Mn derivative of cytochrome b5 was unable to stimulate the metabolism of methoxyflurane. Cytochrome b5 was oligatory for the microsomal metabolism of methoxyflurane, whereas it was not required for the microsomal N-demthylation of benzphetamine. The heme moiety of cytochrome b5 functioned to transfer electrons in this reaction.