ID 1.1.1.325 DE sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming). CA (1) L-threo-7,8-dihydrobiopterin + NADP(+) = H(+) + NADPH + sepiapterin. CA (2) L-threo-tetrahydrobiopterin + 2 NADP(+) = 6-pyruvoyl-5,6,7,8- CA tetrahydropterin + 2 H(+) + 2 NADPH. CC -!- This enzyme, isolated from the bacterium Chlorobium tepidum, CC catalyzes the final step in the de novo synthesis of CC tetrahydrobiopterin from GTP. cf. EC 1.1.1.153. DR Q8KES3, SPRE_CHLTE ; //