(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + 2 NADP(+) = 6-pyruvoyl-5,6,7,8-tetrahydropterin + 2 NADPH + 2 H(+)
(6r)-l-erythro-5,6,7,8-tetrahydrobiopterin + 2 nadp(+) = 6-pyruvoyl-5,6,7,8-tetrahydropterin + 2 nadph + 2 h(+)