This MedLibrary.org supplementary page on Prostanoid is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
Prostanoid is the term used to describe a subclass of eicosanoids consisting of: the prostaglandins (mediators of inflammatory and anaphylactic reactions), the thromboxanes (mediators of vasoconstriction) and the prostacyclins (active in the resolution phase of inflammation.)
- See also main articles at Prostaglandin, Prostacyclin and Thromboxane
Biosynthesis
Cyclooxygenase (COX) catalyzes the conversion of the free essential fatty acids to prostanoids by a two-step process. In the first step, two molecules of O2 are added as two peroxide linkages and a 5-member carbon ring is forged near the middle of the fatty acid chain. This forms the short-lived, unstable intermediate Prostaglandin G (PGG). One of the peroxide linkages sheds a single oxygen, forming PGH. (See diagrams and more detail at Cyclooxygenase). All other prostanoids originate from PGH (as PGH1, PGH2, or PGH3).
Figure 1 shows how PGH2 (derived from Arachidonic acid) is converted:
- By PGE synthetase into PGE (which in turn is converted into PGF)
- By PGD synthetase into PGD
- By Prostacyclin synthase into prostacyclin (PGI2)
- By Thromboxane synthase into thromboxanes
The three classes of prostanoids have distinctive rings in the center of the molecule. They differ in their structures. The PGH compounds (parents to all the rest) have a 5-carbon ring, bridged by two oxygens (a peroxide.) The derived prostaglandins contain a single, unsaturated 5-carbon ring. In prostacyclins, this ring is conjoined to another oxygen-containing ring. In thromboxanes the ring becomes a 6-member ring with one oxygen.
Production of PGE2 in bacterial and viral infections appears to be stimulated by certain cytokines, e.g., interleukin-1.[1]
See also
|
|||||||||||
References
- ^ University of Kansas Medical Center (2004). "Eicosanoids and Inflammation" (PDF). Retrieved on 2007-01-05.
 |
This biochemistry article is a stub. You can help Wikipedia by expanding it. |
Wikipedia content modification information:
- This page was last modified on 22 September 2008, at 06:11.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Prostanoid".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.