| Platelet-activating factor | |
|---|---|
| Identifiers | |
| CAS number | 74389-68-7 |
| PubChem | 108156 |
| ChemSpider | 26286744 |
| MeSH | Platelet+Activating+Factor |
| IUPHAR ligand | 1831 |
| Jmol-3D images | Image 1 |
|
|
|
|
| Properties | |
| Molecular formula | C26H54NO7P |
| Molar mass | 523.68 g mol−1 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Platelet-activating factor, also known as a PAF, PAF-acether or AGEPC (acetyl-glyceryl-ether-phosphorylcholine) is a potent phospholipid activator and mediator of many leukocyte functions, including platelet aggregation and degranulation, inflammation, and anaphylaxis. It is also involved in changes to vascular permeability, the oxidative burst, chemotaxis of leukocytes, as well as augmentation of arachidonic acid metabolism in phagocytes.
It is produced in response to specific stimuli by a variety of cell types, including neutrophils, basophils, injured tissue, monocytes/macrophages, platelets, and endothelial cells.
Contents |
Several molecular species of platelet-activating factor that vary in the length of the O-alkyl side-chain have been identified.
It is an important mediator of bronchoconstriction.
It causes platelets to aggregate and blood vessels to dilate. Thus, it is important to the process of hemostasis. At a concentration of 10-12 mol/L, PAF causes life threatening inflammation of the airways to induce asthma like symptoms.
Toxins such as fragments of destroyed bacteria induce the synthesis of PAF, which causes a drop in blood pressure and reduced volume of blood pumped by the heart, which leads to shock and possibly death.
It was discovered by French immunologist Jacques Benveniste in the early 1970s.[1][2] Its structure was elucidated by Constantinos A. Demopoulos in 1979.[3]
PAF is biosynthesized from lysophosphatidylcholine (LPC) and acetyl CoA by the enzyme LPC acetyltransferase (LPCAT). It is also derived from 2-acetyl monoalkylglycerol ether by phosphocholine transferase.
It is degraded (thereby terminating its capacity to act as a signaling molecule) by a group of enzymes called PAF acetylhydrolases (PAFAHs), which are related to phospholipase A2.
|
||||||||||||||||
|
|||||||||||