Cytochrome P450 systems

Mitochondrial cytochrome P450 systems are found in steroidogenic tissues such as adrenal cortex, testis, ovary, and placenta and are concerned with the biosyn-... 

Lipids are also components of the cytochrome P450 system. The preferred lipid is phosphatidylcholine, which is the major lipid found in membranes of the endoplasmic reticulum. 

FIGURE 3.1 Bacterial oxygenation systems (excluding cytochrome P450 systems). (From Neilson, A.H. and Allard, A.-S. Microbial metabolism of PAHs and heteroarenes, The Handbook of Environmental Chemistry, Vol. 3J, pp. 1-80, Springer, 1998. With permission.)... 

P450 systems (Sariaslani 1991), their widespread role in the transformation of xenobiotics (Smith and Davis 1968), and their occurrence and activities in yeasts (Kappeli 1986). The essential features of prokaryotic and eukaryotic cytochrome P450 systems are compared in Figure 3.17. 

Unusual aspects of bacterial cytochrome P450 systems are worth pointing out ... 

The hydroxylation of steroids at various positions is carried out by a range of fungi, and probably involves the cytochrome P450 system (Breskvar and Hudnik-Plevnik 1977). 

The aerobic degradation of cycloalkanes has been examined in both monocyclic and polycyclic snb-strates. In all of them, monooxygenation is the first step and this is sometimes accomplished by cytochrome P450 systems. Reviews of the degradation of alicyclic componnds inclnding monoterpenes... 

Monooxygenation mediated by the cytochrome P450 system of Streptomyces has been observed in oxaarenes ... 

Cytochrome P450 System - Drug-metabolizing Enzymes... 

Nemeroff CB, DeVane CL, Pollack BG. Newer antidepressants and the cytochrome P450 system. Am J Psychiatry 1996 153 311-320. 

The cytochrome P450 system is actually a family of related liver enzymes. Each specific enzyme within this family is called an isoenzyme. New isoenzymes within the cytochrome P450 system are constantly being discovered. The 1A2, 2C9/2C19, 2D6, and 3A4 isoenzymes are the best understood. Table 3.10 shows the impact of the newer antidepressants on particular cytochrome P450 isoenzymes and the drugs that may be affected. 

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