Reaction catalyzed by delphinidin 3,5-di-O-glucoside 3'-O-glucosyltransferase (2.4.1.238)

		+			=			+
	UDP-glucose	+		delphinidin 3,5-di-O-beta-D-glucoside	=		UDP	+		delphinidin 3,5,7-tri-O-beta-D-glucoside