PGI synthase (PGIS) catalyzes the conversion of PGH2 to PGI2 (prostacyclin). Human lung PGIS is a 56 kDa protein. The cloned bovine and human enzymes contain 500 amino acids and have a calculated molecular mass of 56,629 and 57,103, respectively.1,2,3 There is 88% homology between human and bovine PGIS.WARNING This product is not for human or veterinary use.