Sepiapterin reductase

• OMIM: 182125
• UniProt: P35270

Sepiapterin reductase (SPR) is the enzyme in eukaryotes, catalyzes the reduction of and sepiapterin 6- pyruvoyl -5 ,6,7,8- tetrahydropterin. These are the final steps in the biosynthesis of pterins, which form the backbone for several vitamins and cofactors. SPR is localized in the cytoplasm. Mutations in the SPR gene of the people can SPR deficiency, and this cause a rare genetic disease.

Occurrence

From extracts of rat liver enzyme was obtained and purified in the 1960s, which catalyzed the reduction of sepiapterin to dihydrobiopterin. Also from insects as well as organs of mice, humans and other organisms sepiapterin reductases were isolated. The most abundant sources for SPRs are erythrocytes, liver and brain tissue. SPRs some have been cloned and sequenced. An X-ray structure analysis of the SPR from mice revealed that this is a homodimer with 261 amino acids per monomer.

SPR is also demonstrated in Dictyostelium.

Function

Biochemistry

Together with the cofactor NADPH catalyzed the enzyme reduction (hydrogenation ) of the carbonyl group of the 7,8- Sepiapterins to dihydrobiopterin. In the biosynthesis of 5,6,7,8- tetrahydrobiopterin is in the hydrogenation of precursors, including 6- pyruvoyl -5 ,6,7,8- tetrahydropterins responsible.

Role in the metabolism

SPR acts in the metabolism of many eukaryotes in the synthesis of pigment dyes.

In pterin metabolism of the human cerebrospinal fluid are produced with the participation of SPR neurotransmitters.

Deficiency

A lack of SPR was clinically described as a treatable congenital defect in the pterin metabolism. The successful treatment was about 2-5 years of substitution therapy of affected youth.