Oxygen cytochrome P450 biotransformations

Cytochrome P450 monooxygenases (P450s) have significant potential in biotransformation applications because their ability to insert molecular oxygen regiospecifically and... 

Phase I oxidation generally is described as the addition of an oxygen atom (e.g., as an hydroxyl moiety) to the parent molecule. Phase I oxidation is carried out by multiple enzyme pathways, including the various isoforms of the cytochrome P450 (CYP) family and the non-P450 biotransformation enzymes such as flavin-containing monooxygenase (FMO) and monamine oxidase (MAO). 

The cytochrome P450 (GYP) family of enzymes are the major catalysts that are responsible for a variety of oxidation reactions associated with the biotransformation of many xenobiotics that can be used to illustrate several concepts of toxication and detoxication in a chemistry course. The main function of this group of isozymes is to insert one atom of oxygen into a substrate thereby increasing hydrophilicity or water solubility. These enzymes are haem-containing proteins containing a reduced iron species essential for transferring electrons and work in concert with coenzymes NADPH and NADPH reductase. 

Cytochrome P450 enzymes are the most widespread, active, and most versatile in their xenobiotic Phase I transformation activity. These enzymes are composed of heme-containing enzymes in the ferric ion state. In transformations the ferric ion is reduced to the ferrous ion that can bind Oj and CO. These enzymes basically add oxygen or remove hydrogen in a step-wise process to generate Phase I biotransformation products. Most cytochrome P450 transformations require an additional enzyme (co-enzyme) to assist in the transfer of electrons. Cytochrome P-450 enzymes carry out many kinds of oxidations - hydroxylations, epoxidations, heteroatom oxidations, N-hydroxylations, dealkylations, ester hydrolysis, and dehydrogenation. 

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