In enzymology, a prostaglandin-D synthase is an enzyme that catalyzes the chemical reaction Thus, the substrate of this enzyme is (5Z,13E)-(15S)-9alpha,11alpha-epidioxy-15-hydroxyprosta-5,13-dienoate, whereas its product is (5Z,13E)-(15S)-9alpha,15-dihydroxy-11-oxoprosta-5,13-dienoate. This enzyme belongs to the family of isomerases, specifically a class of other intramolecular oxidoreductases. The systematic name of this enzyme class is (5,13)-(15S)-9alpha,11alpha-epidioxy-15-hydroxyprosta-5,13-dienoate Delta-isomerase. Other names in common use include prostaglandin-H2 Delta-isomerase, prostaglandin-R-prostaglandin D isomerase, and PGH-PGD isomerase. This enzyme participates in arachidonic acid metabolism. In March 2012 American scientists reported a discovery that shows this enzyme triggers male baldness According to the discovery, levels of this enzyme are elevated in the cells of hair follicles located in bald patches on the scalp, but not in hairy areas. The research could lead to a cream to treat baldness.

Structural studies

As of late 2001, 7 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , and.