Reaction catalyzed by 6,7-dihydropteridine reductase (1.5.1.34)

		+		NAD(P)H	=			+		NAD(P)+
	quinonoid 6,7-dimethyl-7,8-(6H)-dihydropterin	+		NAD(P)H	=		6,7-dimethyl-5,6,7,8-tetrahydropterin	+		NAD(P)+