Thromboxane A synthase

Thromboxane A synthase (TXAS) is an enzyme that plays a crucial role in the biosynthesis of thromboxane - a member of the eicosanoid family of lipid molecules involved in the body's inflammatory response and homeostasis. TXAS is the enzyme responsible for the conversion of prostaglandin H2 (PGH2) to thromboxane A2 (TXA2), a potent vasoconstrictor and platelet aggregator.

Function

Thromboxane A synthase is found primarily in platelets, macrophages, and endothelial cells. It catalyzes the conversion of PGH2 to TXA2. This reaction involves the isomerization of the 9,11-endoperoxide group of PGH2 to form a 12,14-dioxapentacyclic ring system in TXA2.

TXA2 is a potent vasoconstrictor and platelet aggregation inducer, playing a significant role in blood clotting and inflammation. It is also involved in the regulation of blood pressure and blood flow to various organs.

Clinical significance

Abnormalities in TXAS activity can lead to a variety of health conditions. Overproduction of TXA2 can lead to excessive platelet aggregation, which can result in thrombosis, a condition that can cause heart attacks and strokes. Conversely, reduced TXAS activity can lead to impaired blood clotting, potentially resulting in excessive bleeding.

Inhibitors of TXAS, such as the drug aspirin, are used to reduce the risk of thrombosis in patients with a high risk of heart attacks or strokes. Aspirin works by irreversibly inhibiting TXAS, thereby reducing the production of TXA2 and decreasing platelet aggregation.

See also

• Eicosanoid
• Prostaglandin-endoperoxide synthase
• Thromboxane