Reaction catalyzed by prostaglandin-I synthase (5.3.99.4)

		=
	(5Z,13E)-(15S)-9alpha,11alpha-epidioxy-15-hydroxyprosta-5,13-dienoate	=		(5Z,13E)-(15S)-6,9alpha-epoxy-11a,15-dihydroxyprosta-5,13-dienoate