The cytochrome P450 superfamily (officially abbreviated as CYP) is a large and diverse group of enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s. The function of most CYP enzymes is to catalyze

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 the oxidation

Redox

Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 of organic substances

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

. The substrates of CYP enzymes include metabolic

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 intermediates such as lipid

Lipid

Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

s and steroid

Steroid

A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...

al hormones, as well as xenobiotic

Xenobiotic

A xenobiotic is a chemical which is found in an organism but which is not normally produced or expected to be present in it. It can also cover substances which are present in much higher concentrations than are usual...

 substances such as drugs and other toxic chemicals. CYPs are the major enzymes involved in drug metabolism

Drug metabolism

Drug metabolism is the biochemical modification of pharmaceutical substances by living organisms, usually through specialized enzymatic systems. This is a form of xenobiotic metabolism. Drug metabolism often converts lipophilic chemical compounds into more readily excreted polar products...

 and bioactivation, accounting for about 75% of the total number of different metabolic reactions.

The most common reaction catalyzed by cytochromes P450 is a monooxygenase

Monooxygenase

Monooxygenases are enzymes that incorporate one hydroxyl group into substrates in many metabolic pathways. In this reaction, two atoms of dioxygen are reduced to one hydroxyl group and one H2O molecule by the concomitant oxidation of NADH.-Classification:...

 reaction, e.g., insertion of one atom of oxygen into an organic substrate (RH) while the other oxygen atom is reduced

Redox

Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 to water:

RH + O₂ + 2H⁺ + 2e^– → ROH + H₂O


Cytochromes P450 (CYPs) belong to the superfamily of proteins containing a heme

Heme

A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

 cofactor

Cofactor (biochemistry)

A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 and, therefore, are hemoprotein

Hemoprotein

A hemeprotein , or heme protein, is a metalloprotein containing a heme prosthetic group- an organic compound that allows a protein to carry out a function that it cannot do alone....

s.