Isolation and comparison of endoplasmic reticulum membranes and their mixed function oxidase activities from mammalian extrahepatic tissues.
Isolation and comparison of endoplasmic reticulum membranes and their mixed function oxidase activities from mammalian extrahepatic tissues.
复制标题
哺乳动物肝外组织内质网膜及其混合功能氧化酶活性的分离和比较。
DOI：
10.1016/0163-7258(79)90042-1
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发表时间：
1979
影响因子：
13.5
通讯作者：
S. Orrenius
中科院分区：
文献类型：
--
作者：
M. Burke;S. Orrenius
任何研究过肝外微粒体混合功能氧化酶的人都认识到与这些研究相关的特殊问题。尽管分离相当纯的微粒体组分，并测定细胞色素P-450和细胞色素P-450- 1相关的混合功能氧化酶活性，在肝脏中相对容易进行，但在肝外组织中却很少如此。许多这样的器官富含结缔组织，并且由内质网发育不良的细胞组成，因此，在均质化和差速离心时，以低产量产生微粒体组分，并且经常被其他亚细胞器污染。此外，在大多数肝外组织中，细胞色素P-450的水平远低于肝脏，因此即使是线粒体细胞色素或血红蛋白的轻微污染也会严重影响细胞色素P-450的光谱研究。细胞色素P-450- 1连接的多功能氧化酶活性测定常因反应速率低而困难。最后，大多数的肝外组织含有相当大的异质性的细胞群体，呈现本地化的混合功能氧化酶系统的特定细胞类型的困难或不可能与目前可用的分离techniques.In尽管所有这些困难，有越来越多的研究与肝外混合功能氧化酶在最近几年。这可能不是由于普遍认为这些酶对整体药物生物转化的重要性，而是由于个体肝外组织中特定混合功能氧化酶反应的生理学、药理学和毒理学意义，以及进一步阐明和区分细胞色素P-450的各种功能的愿望。在这两个方面都已取得相当大的进展。本文的目的是对哺乳动物肝外微粒体混合功能氧化酶的各种特性进行综述。由于肝脏混合功能氧化酶系统的特点是最好的，我们选择比较各种肝外组织的肝脏，而不是他们之间。虽然我们的报告已经相当详细，但不可能包括肝外组织中混合功能氧化酶的所有主要方面;为此，我们参考了几篇更专门的综述（弯曲和Hook，1974; Brandenburger Brown，1974; Juchau，1976）。肠道植物群对异生物质生物转化的贡献，本章没有涉及，Scheline（1973）对此进行了综述。
Anyone who has investigated extrahepatic microsomal mixed function oxidases realizes the special problems that are associated with such studiesl Whereas isolation of a reasonably pure microsomal fraction, and assays of cytochrome P-450 and cytochrome P-450-1inked mixed function oxidase activities, are relatively easily performed with liver, this is rarely true for extrahepatic tissues. Many such organs are rich in connective tissue and are composed of cells with a poorly developed endoplasmic reticulum and thus, upon homogenization and differential centrifugation, produce microsomal fractions in low yields and often contaminated with other subcellular organelles. Moreover, in most extrahepatic tissues, the levels ofcytochrome P-450 are much lower than in liver, so that even a slight contamination by mitochondrial cytochromes or by hemoglobin can drastically affect spectral studies on cytochrome P-450. Assays of cytochrome P-450-1inked mixed function oxidase activities are often made difficult by low reaction rates. Finally, most of the extrahepatic tissues contain cell populations of considerable heterogeneity, rendering localization of the mixed function oxidase system to a specific cell type difficult or impossible with presently available isolation techniques.In spite of all these difficulties there have been an increasing number of studies concerned with extrahepatic mixed function oxidases during recent years. This is probably not due to a general belief in the importance of these enzymes for overall drug biotransformation, but rather to the physiological, pharmacological and toxicological implications of specific mixed function oxidase reactions in the individual extrahepatic tissues, as well as to a desire to further elucidate and differentiate the various functions of cytochrome P-450. Considerable progress has already been made in both these respects. The purpose of this contribution is to present an overview of various characteristics of mammalian extrahepatic microsomal mixed function oxidases. Since the hepatic mixed function oxidase system is best characterized, we have chosen to compare the various extrahepatic tissues to the liver rather than between themselves. Although we have been rather detailed in our presentation, it has not been possible to include all major aspects of mixed function oxidases in extrahepatic tissues; for this purpose we refer to several more specialized reviews (Bend and Hook, 1974; Brandenburger Brown, 1974; Juchau, 1976). The contribution of the gut flora to the biotransformation of xenobiotics, which has not been included in this chapter, has been reviewed by Scheline (1973).