This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5,6,7,8-tetrahydropteridine:NAD(P)+ oxidoreductase. Other names in common use include 6,7-dihydropteridine:NAD(P)H oxidoreductase, DHPR, NAD(P)H:6,7-dihydropteridine oxidoreductase, NADH-dihydropteridine reductase, NADPH-dihydropteridine reductase, NADPH-specific dihydropteridine reductase, dihydropteridine (reduced nicotinamide adenine dinucleotide), reductase, dihydropteridine reductase, dihydropteridine reductase (NADH), and 5,6,7,8-tetrahydropteridine:NAD(P)H+ oxidoreductase.
Clinical significance
Dihydropteridine reductase deficiency is a defect in the regeneration of tetrahydrobiopterin. Many patients have significant developmental delays despite therapy, develop brain abnormalities, and are prone to sudden death. The reason is not completely clear, but might be related to the accumulation of dihydrobiopterin and abnormal metabolism of folic acid.[1] 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).[2] Dihydropteridine reductase deficiency is treated with tyrosine supplements, a controlled diet which is lacking in phenylalanine,[3] well as supplementation of L-DOPA.
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP+ or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source'). NADPH is the reduced form, whereas NADP+ is the oxidized form. NADP+ is used by all forms of cellular life.
Tetrahydrobiopterin deficiency (THBD, BH4D) is a rare metabolic disorder that increases the blood levels of phenylalanine. Phenylalanine is an amino acid obtained normally through the diet, but can be harmful if excess levels build up, causing intellectual disability and other serious health problems. In healthy individuals, it is metabolised (hydroxylated) into tyrosine, another amino acid, by phenylalanine hydroxylase. However, this enzyme requires tetrahydrobiopterin as a cofactor and thus its deficiency slows phenylalanine metabolism.
QDPR is a human gene that produces the enzyme quinoid dihydropteridine reductase. This enzyme is part of the pathway that recycles a substance called tetrahydrobiopterin, also known as BH4. Tetrahydrobiopterin works with an enzyme called phenylalanine hydroxylase to process a substance called phenylalanine. Phenylalanine is an amino acid that is obtained through the diet; it is found in all proteins and in some artificial sweeteners. When tetrahydrobiopterin interacts with phenylalanine hydroxylase, tetrahydrobiopterin is altered and must be recycled to a usable form. The regeneration of this substance is critical for the proper processing of several other amino acids in the body. Tetrahydrobiopterin also helps produce certain chemicals in the brain called neurotransmitters, which transmit signals between nerve cells.
In enzymology, a gluconate 5-dehydrogenase (EC 1.1.1.69) is an enzyme that catalyzes the chemical reaction
In enzymology, a glyoxylate reductase (NADP+) (EC 1.1.1.79) is an enzyme that catalyzes the chemical reaction
In enzymology, a hydroxyphenylpyruvate reductase (EC 1.1.1.237) is an enzyme that catalyzes the chemical reaction
In enzymology, a hydroxypyruvate reductase (EC 1.1.1.81) is an enzyme that catalyzes the chemical reaction
Sepiapterin reductase is an enzyme that in humans is encoded by the SPR gene.
In enzymology, a 1,5-anhydro-D-fructose reductase (EC 1.1.1.263) is an enzyme that catalyzes the chemical reaction
In enzymology, a 6-pyruvoyltetrahydropterin 2'-reductase (EC 1.1.1.220) is an enzyme that catalyzes the chemical reaction
In enzymology, a 15-oxoprostaglandin 13-oxidase (EC 1.3.1.48) is an enzyme that catalyzes the chemical reaction
In enzymology, a 2-coumarate reductase or melilotate dehydrogenase (EC 1.3.1.11) is an enzyme that catalyzes the chemical reaction
In enzymology, a trans-2-enoyl-CoA reductase (NADPH) (EC 1.3.1.38) is an enzyme that catalyzes the chemical reaction
In enzymology, an aldehyde dehydrogenase [NAD(P)+] (EC 1.2.1.5) is an enzyme that catalyzes the chemical reaction
In enzymology, a rubredoxin—NAD(P)+ reductase (EC 1.18.1.4) is an enzyme that catalyzes the chemical reaction
In enzymology, a nitrite reductase [NAD(P)H] (EC 1.7.1.4) is an enzyme that catalyzes the chemical reaction
In enzymology, a pteridine reductase (EC 1.5.1.33) is an enzyme that catalyzes the chemical reaction
In enzymology, a pyrroline-5-carboxylate reductase (EC 1.5.1.2) is an enzyme that catalyzes the chemical reaction
Sepiapterin reductase (L-threo-7,8-dihydrobiopterin forming) (EC 1.1.1.325) is an enzyme with systematic name L-threo-7,8-dihydrobiopterin:NADP+ oxidoreductase. This enzyme catalyses the following chemical reaction
In enzymology, a prostaglandin-F synthase (PGFS; EC 1.1.1.188) is an enzyme that catalyzes the chemical reaction:
↑ Pawlina, Wojciech; Ross, Michael W. (2006). Histology: a text and atlas: with correlated cell and molecular biology. Philadelphia: Lippincott Williams & Wilkins. ISBN0-7817-5056-3.
Further reading
Harano T (1972). "New diaphorases from Bombyx silkworm eggs. NADH/NADPH cytochrome c reductase activity mediated with 6,7-dimethyltetrahydropterin". Insect Biochem. 2 (8): 385–399. doi:10.1016/0020-1790(72)90019-4.
Hasegawa H (January 1977). "Dihydropteridine reductase from bovine liver. Purification, crystallization, and isolation of a binary complex with NADH". Journal of Biochemistry. 81 (1): 169–77. doi:10.1093/oxfordjournals.jbchem.a131432. PMID191436.
Nakanishi N, Hasegawa H, Watabe S (March 1977). "A new enzyme, NADPH-dihydropteridine reductase in bovine liver". Journal of Biochemistry. 81 (3): 681–5. doi:10.1093/oxfordjournals.jbchem.a131504. PMID16875.
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