Molecular function

(5Z,13E)-(15S)-9alpha,11alpha-epidioxy-15-hydroxyprosta-5,13-dienoate E-isomerase activity, PGE isomerase activity, PGE2 isomerase activity, PGH-PGE isomerase activity, Prostaglandin-H(2) E-isomerase activity, endoperoxide isomerase activity, prostaglandin H-E isomerase activity, prostaglandin R-prostaglandin E isomerase activity, prostaglandin endoperoxide E isomerase activity, prostaglandin endoperoxide E2 isomerase activity, prostaglandin-H2 E-isomerase activity

Catalysis of the reaction: prostaglandin H(2) = prostaglandin E(2).