Sepiapterin reductase

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Protein SPR PDB 1z6z.png
Available structures
PDB Ortholog search: PDBe RCSB
Aliases SPR, SDR38C1, sepiapterin reductase (7,8-dihydrobiopterin:NADP+ oxidoreductase)
External IDs MGI: 103078 HomoloGene: 37735 GeneCards: SPR
RNA expression pattern
PBB GE SPR 203458 at fs.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 2: 72.89 – 72.89 Mb Chr 6: 85.13 – 85.14 Mb
PubMed search [1] [2]
View/Edit Human View/Edit Mouse

Sepiapterin reductase is an enzyme that in humans is encoded by the SPR gene.[3][4][5]


Sepiapterin reductase (7,8-dihydrobiopterin:NADP+ oxidoreductase; EC catalyzes the NADPH-dependent reduction of various carbonyl substances, including derivatives of pteridines, and belongs to a group of enzymes called aldo-keto reductases. SPR plays an important role in the biosynthesis of tetrahydrobiopterin.[5]


sepiapterin reductase
EC number
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

Sepiapterin reductase (SPR) catalyzes the chemical reaction

L-erythro-7,8-dihydrobiopterin + NADP+ sepiapterin + NADPH + H+

Thus, the two substrates of this enzyme are L-erythro-7,8-dihydrobiopterin and NADP+, whereas its three products are sepiapterin, NADPH, and a single hydrogen ion (H+).

This enzyme belongs to the family of oxidoreductases, to be specific, those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 7,8-dihydrobiopterin:NADP+ oxidoreductase. This enzyme participates in folate biosynthesis.


Clinical significance[edit]

Sepiapterin reductase deficiency belongs to the rare diseases. The clinical phenotype can include progressive psychomotor retardation, altered tone, seizures, choreoathetosis, temperature instability, hypersalivation, microcephaly, and irritability. Patients with sepiapterin reductase deficiency also manifest dystonia with diurnal variation, oculogyric crises, tremor, hypersomnolence, oculomotor apraxia, and weakness.[7] Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, and for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD).[8]


  1. ^ "Human PubMed Reference:". 
  2. ^ "Mouse PubMed Reference:". 
  3. ^ Ichinose H, Katoh S, Sueoka T, Titani K, Fujita K, Nagatsu T (Oct 1991). "Cloning and sequencing of cDNA encoding human sepiapterin reductase--an enzyme involved in tetrahydrobiopterin biosynthesis". Biochem Biophys Res Commun. 179 (1): 183–189. doi:10.1016/0006-291X(91)91352-D. PMID 1883349. 
  4. ^ Persson B, Kallberg Y, Bray JE, Bruford E, Dellaporta SL, Favia AD, Duarte RG, Jornvall H, Kavanagh KL, Kedishvili N, Kisiela M, Maser E, Mindnich R, Orchard S, Penning TM, Thornton JM, Adamski J, Oppermann U (Feb 2009). "The SDR (short-chain dehydrogenase/reductase and related enzymes) nomenclature initiative". Chem Biol Interact. 178 (1–3): 94–98. doi:10.1016/j.cbi.2008.10.040. PMC 2896744Freely accessible. PMID 19027726. 
  5. ^ a b "Entrez Gene: SPR sepiapterin reductase (7,8-dihydrobiopterin:NADP+ oxidoreductase)". 
  6. ^
  7. ^ Pearl PL, Taylor JL, Trzcinski S, Sokohl A (May 2007). "The pediatric neurotransmitter disorders". J Child Neurol. 22 (5): 606–616. doi:10.1177/0883073807302619. PMID 17690069. 
  8. ^ "Patient registry". 

Further reading[edit]