(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + NADP(+) <=> (6R)-L-erythro-6,7-dihydrobiopterin + NADPH + H(+)
(6r)-l-erythro-5,6,7,8-tetrahydrobiopterin + nadp(+) <=> (6r)-l-erythro-6,7-dihydrobiopterin + nadph + h(+)
(6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + NADP(+) <=> (6R)-L-erythro-6,7-dihydrobiopterin + NADPH + H(+)
(6r)-l-erythro-5,6,7,8-tetrahydrobiopterin + nadp(+) <=> (6r)-l-erythro-6,7-dihydrobiopterin + nadph + h(+)