Definition
Phase 2 enzymes in principle are part of the cellular biotransformation machinery. Cellular biotransformation of xenobiotics and endobiotics, including carcinogen metabolism, may be divided into two sequential phases: phase 1 (oxidation, reduction, and hydrolysis reactions) and phase 2 (conjugation reactions). Phase 2 enzymes traditionally refer to the enzymes catalyzing the conjugation reactions, such as glutathione S-transferase (GST), UDP-glucuronosyltransferase (UGT), N-acetyltransferase (NAT), and sulfotransferase (SULT). However, the term has gradually become broader in scope as it has also been used by an increasing number of investigators for a number of enzymes that catalyze phase 1 reactions, such as epoxide hydrolase (EH), heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase type 1 (NQO1), and enzymes that are not directly involved in the biotransformation process,...
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Zhang, Y. (2011). Phase II Enzymes. In: Schwab, M. (eds) Encyclopedia of Cancer. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-16483-5_4510
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DOI: https://doi.org/10.1007/978-3-642-16483-5_4510
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