HEPATIC MITOCHONDRIAL COUMARIN 7-HYDROXYLASE - COMPARISON WITH THE MICROSOMAL-ENZYME
HEPATIC MITOCHONDRIAL COUMARIN 7-HYDROXYLASE - COMPARISON WITH THE MICROSOMAL-ENZYME
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DOI：
10.1016/0003-9861(88)90063-x
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发表时间：
1988-12-01
影响因子：
3.9
通讯作者：
LANG, MA
中科院分区：
文献类型：
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作者：
HONKAKOSKI, P;KOJO, A;LANG, MA
DBA/2N小鼠肝线粒体细胞色素P450连接的香豆素7-羟化酶（COH）的比活性高达微粒体活性的55%。根据Western印迹和免疫扩散分析以及抗P450 Coh和甲吡酮的抑制研究，有丝分裂P450 Coh具有与相应微粒体酶相同的分子量和免疫化学和催化性质。用DBA/2N和AKR/J小鼠研究的吡唑对这两种蛋白质的诱导及其遗传调控似乎相似。然而，线粒体电子传递系统是不能够支持的COH活性的重组微粒体P450 Coh，虽然酶是完全活跃的微粒体NADPH-细胞色素P450还原酶。这表明这两种蛋白质在与电子转移系统的相互作用方面存在一些差异。抗肾上腺素还蛋白还原酶抗体能有效抑制促有丝分裂COH，但不能抑制用纯化的微粒体P450 Coh和NADPH-P450还原酶重建的COH，证实了这一点。我们以前已经发现，P450 Coh不与抗P450 b或抗P450 c抗体反应，而抗P450 b或抗P450 c抗体在大鼠肝有丝分裂体中识别各自的亚型。虽然来自微粒体和有丝分裂体的P450 Coh具有许多共同的性质，但有丝分裂体P450 Coh代表线粒体P450的一个新亚种。线粒体P450 Coh的某些特征可能是加工和转运到线粒体所必需的翻译后修饰的结果。
The specific activity of cytochrome P450-linked coumarin 7-hydroxylase (COH) of hepatic mitoplasts from DBA/2N mice is up to 55% as great as the microsomal activity. According to Western blot and immunodiffusion analysis and inhibition studies with anti-P450Coh and metyrapone, the mitoplastic P450Coh had the same molecular weight and immunochemical and catalytic properties as the corresponding microsomal enzyme. The inducibility of the two proteins by pyrazole and their genetic regulation, as studied with DBA/2N and AKR/J mice, appears to be similar. However, the mitochondrial electron transfer system was not able to support the COH activity of reconstituted microsomal P450Coh although the enzyme was fully active with the microsomal NADPH-cytochrome P450 reductase. This indicates some differences between the two proteins with respect to their interaction with the electron transfer system. This was confirmed by the ability of anti-adrenodoxin reductase antibody to effectively inhibit the mitoplastic COH but not the COH reconstituted with purified microsomal P450Coh and NADPH-P450 reductase. We have previously found that P450Coh does not react with anti-P450b or anti-P450c antibodies, which recognize respective isoforms in rat liver mitoplasts. While P450Coh from microsomes and mitoplasts possess a number of properties in common, the mitoplast P450Coh represents a new subspecies of mitochondrial P450. Some characteristics of mitoplast P450Coh may be the result of post-translational modifications necessary for processing and translocation into the mitochondria.