2-(prostaglandin H2)-sn-glycero-3-phosphocholine + A + H2O => 2-(prostaglandin G2)-sn-glycero-3-phosphocholine + AH2
2-(prostaglandin h2)-sn-glycero-3-phosphocholine + a + h2o => 2-(prostaglandin g2)-sn-glycero-3-phosphocholine + ah2