Sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming) explained

Sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming)
Ec Number:	1.1.1.325
Cas Number:	9059-48-7

Sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming) is an enzyme with systematic name L-threo-7,8-dihydrobiopterin:NADP⁺ oxidoreductase.^{[1] [2]} This enzyme catalyses the following chemical reaction

(1) L-threo-7,8-dihydrobiopterin + NADP⁺

\rightleftharpoons sepiapterin + NADPH + H⁺

(2) L-threo-tetrahydrobiopterin + 2 NADP⁺

\rightleftharpoons 6-pyruvoyl-5,6,7,8-tetrahydropterin + 2 NADPH + 2 H⁺

This bacterial (Chlorobium tepidum) enzyme catalyses the final step in the de novo synthesis of tetrahydrobiopterin from GTP.

Notes and References

1. Cho SH, Na JU, Youn H, Hwang CS, Lee CH, Kang SO . Sepiapterin reductase producing L-threo-dihydrobiopterin from Chlorobium tepidum . The Biochemical Journal . 340 (Pt 2) . 497–503 . June 1999 . 10333495 . 1220277 . 10.1042/0264-6021:3400497 .
2. Supangat S, Choi YK, Park YS, Son D, Han CD, Lee KH . Expression, purification, crystallization and preliminary X-ray analysis of sepiapterin reductase from Chlorobium tepidum . Acta Crystallographica Section F . 61 . Pt 2 . 202–4 . February 2005 . 16510994 . 1952253 . 10.1107/S174430910403444X .