Conjugating enzyme system, intracellular

A number of enzyme systems have evolved in animals and plants which effectively convert lipophilic xenobiotics to more polar compounds that are efficiently excreted. Phase I enzymes, responsible for oxidation, reduction, and/or hydrolysis, are integrated with phase II or conjugation enzymes for reactions of both types and are normally required for the formation of products polar enough to be readily excreted. The intracellular level of these enzymes, and thus, the capacity for biotransformation, increases in a coordinate fashion in response to exposure to xenobiotic compounds. This response is... 

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