Monooxygenases in Oxidative Biotransformations

Of the various pha.se I reactions that are considered in this chapter, oxidative biotransformation processes are, by far. the most common and important in drug metabolism. The general stoichiometry that describes the oxidation of many xenobiutics (R-H) to their corresponding oxidized metabolites (R-OH) is given by the following equation  

The enzyme systems currying out this biutrunsfurmation arc referred to as mixed-fimclian oxidases or montHixygen-ases. There is a large family that carry out the same basic chemical reaction.s. Their nomenclature is based on 

Must have more than 40% identical amino add sequence 

X Capital teller Subfamily (CYP I A. CYP 2C, CYP JA, etc. I Must bare mure than 55% identical amino add sequence 4. Arabic number Individual enzyme in a subfamily (CYP IA2. CYP 2C9. CYP 2D6. CYP 2EI. CYP 3A4, etc.) 

One important feature of the hepatic cytochrome P-450 mixed-function oxidase system is its ability to metabolize an almost unlimited number of diverse substrates by a variety of oxidative tran.sformations. This versatility is believed 

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