4a-hydroxytetrahydrobiopterin => q-dihydrobiopterin + H2O

Cytosolic pterin-4-alpha-carbinolamine dehydratase (PCDB1) catalyzes the reaction of 4a-hydroxytetrahydrobiopterin to form q-dihydrobiopterin and water (Hauer et al. 1993. The active enzyme is a homotetramer (Ficner et al. 1995); mutations in the PCDB1 gene are associated with mild hyperphenylalanemia in vivo (Citron et al. 1993).

细胞质中四氢生物蝶呤-4-α-羰醇胺脱水酶（PCDB1）催化4a-羟基四氢生物蝶呤与水反应生成q-二氢生物蝶呤（Hauer et al. 1993。《四氢生物蝶呤的活性酶是一种同源四聚体（Ficner et al. 1995）；PCDB1基因突变与体内轻度高苯丙氨酸血症相关（Citron et al. 1993）》。