Platelet activating factor ( PAF, platelet activating factor, PAF ) is a potent phospholipid mediator of inflammation . It is synthesized by many cell types: neutrophils , basophils , platelets and endothelial cells . Participates in inflammation, platelet aggregation, plays a role in the pathogenesis of anaphylactic shock .
| Platelet Activation Factor | |
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| Are common | |
| Chem. formula | C 26 H 54 N 1 O 7 P 1 |
| Physical properties | |
| Molar mass | 523.683 g / mol |
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| Chemspider | |
Content
History
The FAT was discovered in the early 1970s by the French immunologist Jacques Benveniste, and in 1979 Konstantinos Demopoulos established the structure of this compound.
Structure
The molecule of the platelet activating factor has several features.
- In position C1 of the glycerol residue is alkyl , which is connected to the glycerol backbone due to the ether linkage (as opposed to the ester linkage characteristic of most phospholipids). The length of alkyl is typically C16, but may vary. Thus, the platelet activation factor is not so much a specific chemical compound as a group of similar substances with different alkyl chain lengths.
- In the C2 position of the glycerol residue, PAF contains an acetate group (unlike fatty acid residues in most phospholipids). The short length of the acetate residue is important for increasing the solubility in an aqueous medium, which allows PAF to act as a secondary mediator .
- In position C3 of the glycerol residue is the phosphocholine group as well as in numerous phosphatidylcholines .
Synthesis and catabolism
PAF is synthesized from lysophosphatidylcholine and acetyl-Coenzyme A by the enzyme lysophosphatidylcholine acyltransferase . FAT degradation is carried out by the so-called. ФАТ-acetylhydrolase from the phospholipase A2 superfamily, which cleaves the acetyl group.
Function
One of the most important mediators of bronchospasm (bronchoconstriction). It causes platelet aggregation and vasodilation, which indicates its important role in blood coagulation. At a concentration of 1 pmol / l, it causes the most severe inflammation of the bronchial tree, which is comparable to an attack of asthma. Various toxins (including fragments of dead bacteria) stimulate the synthesis of PAF and, as a result, systemic hypotension and a decrease in the pumping function of the left ventricle of the heart, which is fraught with shock and even death.
Notes
Links
- Platelet activation factor: introduction.
- Shimizu T. Lipid mediators in the field of immunity and inflammation ( Ann .) // Annu. Rev. Pharmacol. Toxicol. : journal. - 2009. - Vol. 49 . - P. 123-150 . - DOI : 10.1146 / annurev.pharmtox.011008.145616 . - PMID 18834304 .