Reaction catalyzed by sepiapterin reductase (L-erythro-7,8-dihydrobiopterin forming) (1.1.1.153)
+
2
NADP+
=
+
2
NADPH
+
2
L-erythro-tetrahydrobiopterin
+
2 NADP+
=
6-pyruvoyl-5,6,7,8-tetrahydropterin
+
2 NADPH
+
2 H+