prostaglandin-I synthase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: prostaglandin H(2) = prostaglandin I(2). [EC:5.3.99.4, RHEA:23580]

Prostaglandin-I synthase (PGIS) activity catalyzes the conversion of prostaglandin H2 (PGH2) to prostacyclin (PGI2). This enzyme is a member of the cytochrome P450 family and is primarily expressed in vascular endothelial cells. PGH2 is a precursor molecule for a variety of prostaglandins, including thromboxane A2 (TXA2) which promotes platelet aggregation and vasoconstriction.

PGIS activity is crucial for maintaining vascular homeostasis by opposing the actions of TXA2. PGI2 is a potent vasodilator and inhibits platelet aggregation, thus contributing to the prevention of thrombosis and blood clotting.

The molecular mechanism of PGIS activity involves a series of enzymatic steps. First, PGH2 binds to the active site of the enzyme. Then, a heme iron atom in the enzyme facilitates the transfer of an oxygen atom from molecular oxygen to the 9-hydroxyl group of PGH2. This oxidation step generates a carbocation intermediate that undergoes a ring opening and a subsequent rearrangement to form PGI2.

PGIS activity is essential for maintaining blood vessel integrity and preventing thrombosis. Inhibition of PGIS activity can lead to vasoconstriction, platelet aggregation, and an increased risk of cardiovascular disease. Conversely, activation of PGIS activity may have therapeutic benefits in conditions like hypertension and atherosclerosis.'
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Proteins (2)

Compounds (6)