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Prostaglandin H2
Prostaglandin H2 is a type of prostaglandin and a precursor for many other biologically significant molecules. It is synthesized from arachidonic acid in a reaction catalyzed by a cyclooxygenase enzyme. The conversion from Arachidonic acid to Prostaglandin H2 is a two step process. First, COX-1 catalyzes the addition of two free oxygens to form the 1,2-Dioxane bridge and a peroxide functional group to form Prostaglandin G2. Second, COX-2 reduces the peroxide functional group to a Secondary alcohol, forming Prostaglandin H2. Other peroxidases like Hydroquinone have been observed to reduce PGG2 to PGH2. PGH2 is unstable at room temperature, with a half life of 90-100 seconds, so it is often converted into a different prostaglandin. It is acted upon by: * Prostacyclin synthase to create prostacyclin * Thromboxane-A synthase to create thromboxane A2 and 12-(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) (see 12-Hydroxyheptadecatrienoic acid) * Prostaglandin D2 synthase to cre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin
The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derived enzymatically from the fatty acid arachidonic acid. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring. They are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. The structural differences between prostaglandins account for their different biological activities. A given prostaglandin may have different and even opposite effects in different tissues in some cases. The ability of the same prostaglandin to stimulate a reaction in one tissue and inhibit the same reaction in another tissue is determined by the type of receptor to which the prostaglandin binds. They act as autocrine or paracrine factors with their target cells present in the immediate vicinity of the site of their secret ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostacyclin
Prostacyclin (also called prostaglandin I2 or PGI2) is a prostaglandin member of the eicosanoid family of lipid molecules. It inhibits platelet activation and is also an effective vasodilator. When used as a drug, it is also known as epoprostenol. The terms are sometimes used interchangeably. Function Prostacyclin (PGI2) chiefly prevents formation of the platelet plug involved in primary hemostasis (a part of blood clot formation). It does this by inhibiting platelet activation. It is also an effective vasodilator. Prostacyclin's interactions contrast with those of thromboxane (TXA2), another eicosanoid. Both molecules are derived from arachidonic acid, and work together with opposite platelet aggregatory effects. These strongly suggest a mechanism of cardiovascular homeostasis between these two hormones in relation to vascular damage. Medical uses It is used to treat pulmonary arterial hypertension (PAH), pulmonary fibrosis, as well as atherosclerosis. Specifically, epopr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostanoid Synthesis
Prostanoids are active lipid mediators that regulate inflammatory response. Prostanoids are 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). Prostanoids are seen to target NSAIDS which allow for therapeutic potential. Prostanoids are present within areas of the body such as the gastrointestinal tract, urinary tract, respiratory and cardiology systems, reproductive tract and vascular system. Prostanoids can even be seen with aid to the water and ion transportation within cells. Prostanoids help release prostaglandins upon activation, receptors may open possibilities for treatments within different systems. History Prostanoids were discovered through biological research studies conducted in the 1930s. The first discovery was seen through semen by a Swedish Physiologist Ulf von Euler, who assum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thromboxane Receptor
The thromboxane receptor (TP) also known as the prostanoid TP receptor is a protein that in humans is encoded by the ''TBXA2R'' gene, The thromboxane receptor is one among the five classes of prostanoid receptors and was the first eicosanoid receptor cloned. The TP receptor derives its name from its preferred endogenous ligand thromboxane A2. Gene The gene responsible for directing the synthesis of the thromboxane receptor, ''TBXA2R'', is located on chromosome 19 at position p13.3, spans 15 kilobases, and contains 5 exons. ''TBXA2R'' codes for a member of the G protein-coupled super family of seven-transmembrane receptors. Heterogeneity Molecular biology findings have provided definitive evidence for two human TP receptor subtypes. The originally cloned TP from placenta (343 amino acids in length) is known as the α isoform and the splice variant cloned from endothelium (with 407 amino acids), termed the β isoform. The first 328 amino acids are the same for both isoforms, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin E2
Prostaglandin E2 (PGE2), also known as dinoprostone, is a naturally occurring prostaglandin with oxytocic properties that is used as a medication. Dinoprostone is used in labor induction, bleeding after delivery, termination of pregnancy, and in newborn babies to keep the ductus arteriosus open. In babies it is used in those with congenital heart defects until surgery can be carried out. It is also used to manage gestational trophoblastic disease. It may be used within the vagina or by injection into a vein. PGE2 synthesis within the body begins with the activation of arachidonic acid (AA) by the enzyme phospholipase A2. Once activated, AA is oxygenated by cyclooxygenase (COX) enzymes to form prostaglandin endoperoxides. Specifically, prostaglandin G2 (PGG2) is modified by the peroxidase moiety of the COX enzyme to produce prostaglandin H2 (PGH2) which is then converted to PGE2. Common side effects of PGE2 include nausea, vomiting, diarrhea, fever, and excessive uterine cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin E Synthase
Prostaglandin E synthase (, or PGE synthase) is an enzyme involved in eicosanoid and glutathione metabolism, a member of MAPEG family. It generates prostaglandin E (PGE) from prostaglandin H2. The synthase generating PGE2 is a membrane-associated protein. Isozymes Humans express three prostaglandin-E synthase isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...s, each encoded by a separate gene: References External links * * EC 5.3.99 {{enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin D2
Prostaglandin D2 (or PGD2) is a prostaglandin that binds to the receptor PTGDR (DP1), as well as CRTH2 (DP2). It is a major prostaglandin produced by mast cells – recruits Th2 cells, eosinophils, and basophils. In mammalian organs, large amounts of PGD2 are found only in the brain and in mast cells. It is critical to development of allergic diseases such as asthma. Research carried out in 1989' found PGD2 is the primary mediator of vasodilation (the "niacin flush") after ingestion of niacin (nicotinic acid). A 2012 research paper indicates a causal link between elevated levels of localized PGD2 and hair growth inhibition. Applied topically, the researchers found PGD2 prevents hair growth, and mice that were genetically inclined to produce higher levels of PGD2 had inhibited hair growth. The researchers also found PGD2 levels were much higher in balding scalp tissue than nonbalding scalp tissue, through increased levels of prostaglandin D2 synthase. The paper suggested that i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin D2 Synthase
Prostaglandin-H2 D-isomerase (PTGDS) is an enzyme that in humans is encoded by the ''PTGDS'' gene. Function The protein encoded by this gene is a glutathione-independent prostaglandin D synthase that catalyzes the conversion of prostaglandin H2 (PGH2) to prostaglandin D2 (PGD2). PGD2 functions as a neuromodulator as well as a trophic factor in the central nervous system. PGD2 is also involved in smooth muscle contraction/relaxation and is a potent inhibitor of platelet aggregation. This gene is preferentially expressed in brain. Studies with transgenic mice over-expressing this gene suggest that this gene may be also involved in the regulation of non-rapid eye movement sleep. Furthermore, PTGDS and its product PGD2 are elevated in the bald-scalp areas of men with male pattern baldness (androgenetic alopecia). Clinical use Prostaglandin D2 synthase is used clinically as a diagnostic marker for liquorrhea, that is, to check whether fluid leaking from the nose or ear contai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
12-Hydroxyheptadecatrienoic Acid
1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. In conventions of sign where zero is considered neither positive nor negative, 1 is the first and smallest positive integer. It is also sometimes considered the first of the infinite sequence of natural numbers, followed by 2, although by other definitions 1 is the second natural number, following 0. The fundamental mathematical property of 1 is to be a multiplicative identity, meaning that any number multiplied by 1 equals the same number. Most if not all properties of 1 can be deduced from this. In advanced mathematics, a multiplicative identity is often denoted 1, even if it is not a number. 1 is by convention not considered a prime number; this was not universally accepted until the mid-20th century. Additionally, 1 is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thromboxane A2
Thromboxane A2 (TXA2) is a type of thromboxane that is produced by activated platelets during hemostasis and has prothrombotic properties: it stimulates activation of new platelets as well as increases platelet aggregation. This is achieved by activating the thromboxane receptor, which results in platelet-shape change, inside-out activation of integrins, and degranulation. Circulating fibrinogen binds these receptors on adjacent platelets, further strengthening the clot. Thromboxane A2 is also a known vasoconstrictor and is especially important during tissue injury and inflammation. It is also regarded as responsible for Prinzmetal's angina. Receptors that mediate TXA2 actions are thromboxane A2 receptors. The human TXA2 receptor (TP) is a typical G protein-coupled receptor (GPCR) with seven transmembrane segments. In humans, two TP receptor splice variants – TPα and TPβ – have so far been cloned. Synthesis and breakdown TXA2 is generated from prostaglandin H2 by thromboxa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thromboxane-A Synthase
Thromboxane A synthase 1 (, platelet, cytochrome P450, family 5, subfamily A), also known as TBXAS1, is a cytochrome P450 enzyme that, in humans, is encoded by the ''TBXAS1'' gene. Function This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids, and other lipids. However, this protein is considered a member of the cytochrome P450 superfamily on the basis of sequence similarity rather than functional similarity. This endoplasmic reticulum membrane protein catalyzes the conversion of prostaglandin H2 to thromboxane A2, a potent vasoconstrictor and inducer of platelet aggregation, and also to 12-Hydroxyheptadecatrienoic acid (i.e. 12-(''S'')-hydroxy-5''Z'',8''E'',10''E''-heptadecatrienoic acid or 12-HHT) an agonist of Leukotriene B4 receptors (i.e. BLT2 receptors) and mediator of certain BLT2 receptor actions. The enz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostacyclin Synthase
Prostaglandin-I synthase () also known as prostaglandin I2 (prostacyclin) synthase (PTGIS) or CYP8A1 is an enzyme involved in prostanoid biosynthesis that in humans is encoded by the ''PTGIS'' gene. This enzyme belongs to the family of cytochrome P450 isomerases. Function This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. However, this protein is considered a member of the cytochrome P450 superfamily on the basis of sequence similarity rather than functional similarity. This endoplasmic reticulum membrane protein catalyzes the conversion of prostaglandin H2 to prostacyclin (prostaglandin I2), a potent vasodilator and inhibitor of platelet aggregation. An imbalance of prostacyclin and its physiological antagonist thromboxane A2 contribute to the development of myocardial infarction, stroke, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
