Cyp Family

Introduction
Cytochromes P450 enzymes constitute a large superfamily of haem-thiolate proteins involved in the metamorphosis of a ample variety of both exogenous and endogenetic compounds. They were first discovered in 1955 in rat coloured microsomes and they are characterized by an intense absorption band at 450 nm in the presence of carbon monoxide
The cytochrome P450 (CYP) mixed work out monooxygenases are located on the smooth endoplasmic reticulum of cells passim the body, exclusively the highest concentrations are found in the liver (hepatocytes) and down(p) intestine. These enzymes are responsible for the oxidative (Phase I) metabolism of a wide number of compounds, including many medications. They biotransform lipophilic do drugss to much polar compounds that basin be excreted by the kidneys. The metabolites are usually less busy than the parent compound, although some drugs undergo biotransformation to pharmacologic active agents. In some cases the metabolites can be toxic, carcinogenic or teratogenic.
At least 12 cytochrome P-450 gene families have been identified in humans, although 3 families are involved in the majority of the drug biotransformations; these are the cytochrome P-450 1,2 and 3 (CYP1, CYP2 and CYP3).



The enzymes are divided into families based on amino acid sequence similarities, and each family can be further separated into subfamilies, which are designated by capital letter following the family designation (e.g., CYP3A). Individual enzymes are subsequently indicated by arabic numerals (e.g., CYP3A4). An enzyme belongs to a family when the amino acid sequence possesses more then 40% homology, enzymes with more than 55% homology form a subfamily and someone enzymes can have to 97% homology between the sequences. A single hepatocyte can contain a variety of cytochrome P-450 enzymes. An individual enzyme of cytochrome P-450 may be able of metabolizing many different drugs, but a given drug may be originally metabolized by a single enzyme.
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