Reaction catalyzed by 7alpha-hydroxysteroid dehydrogenase (1.1.1.159)

		+		NAD+	=			+		NADH
	taurochenodeoxycholic acid	+		NAD+	=		2[[3alpha-hydroxy-7,24-dioxo-5beta-cholan-24-yl]amino]ethane sulfonic acid	+		NADH