5-lipoxygenase

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Identifiers
EC number	1.13.11.34
CAS number	9029-60-1
Alt. names
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway

5-Lipoxygenase (5-LO or 5-LOX) is an enzyme that in humans is encoded by the ALOX5 gene on chromosome 10. This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with the incorporation of molecular oxygen (oxygenases). The oxygen incorporated need not be derived from O2. 5-Lipoxygenase catalyzes the production of leukotrienes from arachidonic acid, which are mediators in the pathophysiology of inflammation and allergy.

Function

5-Lipoxygenase catalyzes the first step in the biosynthesis of leukotrienes from arachidonic acid. This involves the conversion of arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE), and subsequently to various leukotrienes such as leukotriene B4 (LTB4), leukotriene C4 (LTC4), and others. These leukotrienes are involved in inflammatory and allergic responses, playing a significant role in conditions such as asthma, rheumatoid arthritis, and colitis.

Clinical Significance

Due to its role in the synthesis of pro-inflammatory leukotrienes, 5-lipoxygenase is a target for pharmaceutical intervention in diseases characterized by chronic inflammation. Inhibitors of 5-lipoxygenase, such as zileuton, are used in the treatment of asthma and other inflammatory conditions to reduce symptoms by limiting leukotriene production.

Genetic Studies

Variations in the ALOX5 gene have been associated with differences in the enzyme's activity and expression, which can affect an individual's susceptibility to asthma and other inflammatory diseases. Polymorphisms in this gene are linked to varied responses to anti-leukotriene drugs, which are important in the personalized medicine approach for treating asthma.

See Also

• Leukotriene
• Arachidonic acid
• Inflammation
• Oxidoreductase