Reaction catalyzed by tryptophan synthase (indole-salvaging) (4.2.1.122)

		+			=			+		H2O
	L-threonine	+		7-azaindole	=		(2S,3S)-2-amino-3-(1H-pyrrolo[2,3-b]pyridin-3-yl)butanoic acid	+		H2O