Reaction catalyzed by N-acetyllactosaminide alpha-2,3-sialyltransferase (2.4.3.6)

		+			=			+
	CMP-N-acetyl-beta-neuraminate	+		4-methylumbelliferyl beta-lactoside	=		CMP	+		alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-Glc