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| * '''Cyclooxygenase''' (COX) is an enzyme involved in the synthesis of [[Prostanoid|prostanoids]], including [[prostaglandins]], [[prostacyclin]], and [[thromboxanes]]. It plays a crucial role in [[inflammation]], pain, and various physiological processes in the body.
| | {{Short description|Enzyme involved in the formation of important biological mediators}} |
| * There are two main isoforms of cyclooxygenase: COX-1 and COX-2.
| | {{Infobox enzyme |
| | | name = Cyclooxygenase |
| | | image = Cyclooxygenase-1 and -2.png |
| | | width = 250 |
| | | caption = Structure of cyclooxygenase-1 and -2 |
| | | EC_number = 1.14.99.1 |
| | | CAS_number = 9055-60-1 |
| | | GO_code = 0004666 |
| | }} |
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| [[File:Prostaglandin synthesis.svg|thumb|Prostaglandin synthesis, involving the action of cyclooxygenase.]] | | '''Cyclooxygenase''' ('''COX''') is an [[enzyme]] that is responsible for the formation of important biological mediators called [[prostaglandins]], which are involved in inflammation and other critical physiological functions. There are two main isoforms of cyclooxygenase: [[COX-1]] and [[COX-2]]. |
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| [[File:Cyclooxygenase.png|thumb|Cyclooxygenase]] | | == Function == |
| | Cyclooxygenase enzymes catalyze the conversion of [[arachidonic acid]] to [[prostaglandin H2]] (PGH2), the precursor of other [[prostaglandins]], [[prostacyclin]], and [[thromboxane]]. These compounds are involved in various physiological processes, including the regulation of [[inflammation]], [[pain]], and [[fever]]. |
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| [[File:Cyclooxygenase-2.png|thumb|Cyclooxygenase-2]] | | == Isoforms == |
| | === COX-1 === |
| | [[COX-1]] is constitutively expressed in most tissues and is involved in the regulation of normal cellular processes, such as the protection of the [[gastric mucosa]], platelet aggregation, and maintenance of [[renal blood flow]]. |
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| [[File:Cyclooxygenase inhibitors.png|thumb|Cyclooxygenase inhibitors]] | | === COX-2 === |
| | [[COX-2]] is an inducible enzyme that is expressed in response to inflammatory stimuli, such as [[cytokines]], [[growth factors]], and [[tumor promoters]]. It is primarily involved in the inflammatory response and is a target for [[nonsteroidal anti-inflammatory drugs]] (NSAIDs). |
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| | == Inhibition == |
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| | Cyclooxygenase inhibitors, such as [[aspirin]] and other [[NSAIDs]], work by blocking the activity of COX enzymes, thereby reducing the production of prostaglandins and alleviating symptoms of inflammation and pain. Selective COX-2 inhibitors, also known as [[coxibs]], were developed to reduce gastrointestinal side effects associated with traditional NSAIDs. |
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| == '''COX-1''' == | | == Clinical significance == |
| | The inhibition of COX enzymes has therapeutic benefits in the treatment of conditions such as [[arthritis]], [[menstrual pain]], and [[cardiovascular disease]]. However, long-term use of COX inhibitors can lead to adverse effects, including [[gastrointestinal bleeding]], [[renal impairment]], and increased risk of [[cardiovascular events]]. |
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| * COX-1 is constitutively expressed in most tissues and has various physiological functions, including:
| | == See also == |
| * '''Gastroprotection''': COX-1-derived prostaglandins help maintain the integrity of the stomach lining by promoting mucus production and reducing acid secretion. | | * [[Prostaglandin synthesis]] |
| * '''Renal Function''': COX-1 plays a role in maintaining renal blood flow and regulating sodium and water balance.
| | * [[Nonsteroidal anti-inflammatory drug]] |
| * '''Platelet Aggregation''': COX-1-derived [[thromboxane A2]] promotes [[platelet aggregation]] and [[blood clot]] formation.
| | * [[Arachidonic acid]] |
| * COX-1 is considered a housekeeping enzyme, responsible for the normal physiological functions mentioned above.
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| == '''COX-2''' == | | == References == |
| | {{Reflist}} |
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| * COX-2, in contrast to COX-1, is an inducible enzyme and is primarily expressed in response to [[inflammation]] and certain pathological conditions. | | == External links == |
| * It is responsible for the production of [[prostaglandins]] and other [[prostanoids]] that are involved in [[inflammation]], pain, and other immune responses.
| | * [https://www.wikimd.com/wiki/Cyclooxygenase Cyclooxygenase on WikiMD] |
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| Functions of COX-2 include:
| | [[Category:Enzymes]] |
| * '''Inflammation''': COX-2-derived prostaglandins mediate the inflammatory response by promoting [[vasodilation]], increased [[vascular permeability]], and recruitment of immune cells to the site of [[inflammation]].
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| * '''Pain and Fever''': COX-2-derived prostaglandins sensitize pain receptors, contributing to the perception of pain. Additionally, they play a role in the hypothalamic regulation of body temperature, leading to fever.
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| * '''Cellular Proliferation''': COX-2 expression is associated with [[cell proliferation]] and tissue remodeling. It is involved in processes such as wound healing and tissue repair.
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| * The inducible nature of COX-2 makes it a target for therapeutic intervention in conditions characterized by inflammation and pain.
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| == '''Mechanism of Action''' ==
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| * The mechanism of action of cyclooxygenase involves the conversion of [[arachidonic acid]], a fatty acid derived from cell membrane [[phospholipids]], into [[prostaglandin H2]] (PGH2), which serves as the precursor for various [[prostanoids]].
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| This process occurs in several steps:
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| * '''Arachidonic Acid Release''': In response to cellular signaling, [[phospholipases]] are activated, leading to the release of [[arachidonic acid]] from cell membrane [[phospholipids]].
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| * '''Cyclooxygenase Activity''': The released arachidonic acid is then converted by cyclooxygenase into [[prostaglandin G2]] (PGG2). This step involves the incorporation of two oxygen molecules into arachidonic acid.
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| * '''Peroxidase Activity''': The PGG2 produced by cyclooxygenase undergoes further transformation by the peroxidase activity of [[cyclooxygenase]], resulting in the formation of [[prostaglandin H2]] (PGH2).
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| * '''Prostanoid Synthesis''': Prostaglandin H2 (PGH2) serves as the precursor for various prostanoids, including [[prostaglandins]], [[prostacyclin]], and [[thromboxanes]]. Additional enzymes in the cells then convert PGH2 into specific prostanoids, each with its own biological effects.
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| * The prostanoids synthesized from the action of cyclooxygenase play crucial roles in mediating inflammation, pain, and other physiological processes in the body.
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| == '''Inhibition of COX''' ==
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| * The therapeutic potential of inhibiting cyclooxygenase lies in modulating the synthesis of [[prostanoids]].
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| * [[Nonsteroidal anti-inflammatory drugs]] (NSAIDs) are a class of medications that inhibit COX activity.
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| They can be categorized into two types:
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| * '''Nonselective COX inhibitors''': These '''drugs inhibit both COX-1 and COX-2'''. Examples include [[aspirin]], [[ibuprofen]], and [[naproxen]]. Nonselective COX inhibitors have [[analgesic]], [[anti-inflammatory]], and [[antipyretic]] effects but may also cause gastrointestinal side effects and affect platelet function.
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| * '''Selective COX-2 inhibitors''': These drugs '''specifically target COX-2''' while sparing COX-1. Examples include [[celecoxib]] and [[rofecoxib]]. Selective COX-2 inhibitors provide anti-inflammatory and analgesic effects with potentially fewer gastrointestinal side effects but have been associated with an increased risk of [[Cardiovascular event|cardiovascular events]].
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| * The inhibition of COX activity by NSAIDs reduces the production of [[prostanoids]], leading to decreased [[inflammation]], pain relief, and other therapeutic effects. However, it is important to consider the potential side effects and individual patient factors when using these medications.
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| {{stub}}
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| {{Metabolism of complex lipids}}
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| {{Prostanoidergics}}
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| {{Dioxygenases}}
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| {{Enzymes}}
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| {{Portal bar|Biology|border=no}}
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| [[Category:Prostaglandins]]
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| [[Category:EC 1.14.99]] | | [[Category:EC 1.14.99]] |
| [[Category:Integral membrane proteins]]
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| [[Category:Enzymes]]
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| [[Category:Prostaglandins]] | | [[Category:Prostaglandins]] |
| [[Category:Nonsteroidal anti-inflammatory drugs]] | | [[Category:Inflammation]] |
| [[Category:Pharmacology]]
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Enzyme involved in the formation of important biological mediators
Structure of cyclooxygenase-1 and -2
Cyclooxygenase (COX) is an enzyme that is responsible for the formation of important biological mediators called prostaglandins, which are involved in inflammation and other critical physiological functions. There are two main isoforms of cyclooxygenase: COX-1 and COX-2.
Function
Cyclooxygenase enzymes catalyze the conversion of arachidonic acid to prostaglandin H2 (PGH2), the precursor of other prostaglandins, prostacyclin, and thromboxane. These compounds are involved in various physiological processes, including the regulation of inflammation, pain, and fever.
Isoforms
COX-1
COX-1 is constitutively expressed in most tissues and is involved in the regulation of normal cellular processes, such as the protection of the gastric mucosa, platelet aggregation, and maintenance of renal blood flow.
COX-2
COX-2 is an inducible enzyme that is expressed in response to inflammatory stimuli, such as cytokines, growth factors, and tumor promoters. It is primarily involved in the inflammatory response and is a target for nonsteroidal anti-inflammatory drugs (NSAIDs).
Inhibition
Cyclooxygenase inhibitors, such as aspirin and other NSAIDs, work by blocking the activity of COX enzymes, thereby reducing the production of prostaglandins and alleviating symptoms of inflammation and pain. Selective COX-2 inhibitors, also known as coxibs, were developed to reduce gastrointestinal side effects associated with traditional NSAIDs.
Clinical significance
The inhibition of COX enzymes has therapeutic benefits in the treatment of conditions such as arthritis, menstrual pain, and cardiovascular disease. However, long-term use of COX inhibitors can lead to adverse effects, including gastrointestinal bleeding, renal impairment, and increased risk of cardiovascular events.
See also
References
<references group="" responsive="1"></references>
External links
