Xenobiotic metabolism peroxidase

Hollenberg, P. (1992). Mechanisms of cytochrome P450 and peroxidase-catalyzed xenobiotic metabolism. The FASEB Journal Official Publication of the Federation of American Societies for Experimental Biology, 6, 686—694. 

Although most studies have focused on the role of GSH S-transferases in xenobiotic metabolism, these enzymes also have multiple endogenous metabolic functions. For example, the biosynthesis of leukotriene C4, the GSH conjugate of the epoxide leukotriene A, was shown to be catalyzed by the GSH S-transferase from Dirofilaria immitis (54). In addition to the selenium-dependent GSH peroxidase, eukaryotic cells have selenium-independent GSH peroxidase activity that is attributable to GSH... 

PAHs are metabolized by a variety of xenobiotic-metabolizing enzymes (Baird et al., 2005). CYP and epoxide hydrolase eonvert the PAH into PAH-diols and these products are transformed in metabolites, potentially, carcinogenic, by the CYP aetion, forming PAH diol-epoxides or by the Aldo-keto-reductase action, generating PAH o-quinones. PAHs can be also activated by CYP and by peroxidases, forming the reactive cations radicals, which bind, covalently, to DNA. Intermediary products formed are still metabolized by enzymes of phase 11, resulting in metabolites more polars and soluble in water becoming ready to be excreted by the body (Shimada, 2006). 

Heteroatom-demethylation reactions catalyzed by peroxidases could be of significant importance in the activation of drugs (xenobiotics) in plants and be responsible for some plant diseases [91]. Likewise, O-dealkylation reactions catalyzed by peroxidases may be important in the metabolism of tetrahydroprotoberberine (XV) and protoberberine (XVI) alkaloids in the plant families Berberidaceae and Ranunculaceae [50]. 

Various peroxidases are progressively being recognized as important enzymes in drug metabolism. Several cytochrome P450 enzymes have been shown to have peroxidase activity (40). Protaglandin-endoperoxide synthase (EC 1.14.99.1) is able to use a number of xenobiotics as cofactors in a reaction of cooxidation (41). And finally, a variety of other peroxidases may oxidize drugs, e.g., catalase (EC 1.11.1.6) and myeloperoxidase (donor hydro-gen-peroxide oxidoreductase EC 1.11.1.7) (42). 

---