| Description | Biopterin, also known as tetrahydrobiopterin or BH4, belongs to the class of organic compounds known as biopterins and derivatives. These are coenzymes containing a 2-amino-pteridine-4-one derivative. Biopterin or tetrahydrobiopterin is also classified as a pterin derivative that consists of pterin group bearing an amino, an oxo and a 1,2-dihydroxypropyl substituent at positions 2, 4 and 6, respectively. Biopterin compounds found within the animals include BH4 (tetrahydrobiopterin), the free radical BH3, and BH2 (also a free radical, called Dihydrobiopterin). BH2 is produced in the synthesis of L-DOPA, dopamine, norepinephrine and epinephrine. It is restored to the required cofactor tetrahydrobiopterin by the enzyme dihydrobiopterin reductase. Tetrahydrobiopterin (BH4) is a cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline). It is also a cofactor for the production of nitric oxide (NO) by the nitric oxide syntheses. Tetrahydrobiopterin is biosynthesized from guanosine triphosphate (GTP) by three chemical reactions mediated by the enzymes GTP cyclohydrolase I (GTPCH), 6-pyruvoyltetrahydropterin synthase (PTPS), and sepiapterin reductase (SR). Biopterin synthesis disorders are a cause of hyperphenylalaninemia. There are 3 distinct forms of phenylketonuria or hyperphenylalaninemia, each caused by lack of aromatic amino acid hydroxylase enzymes. The variant forms of hyperphenylalaninemia that are caused by the lack of dihydropteridine reductase or tetrahydrobiopterin are characterized by severe neurological deterioration, impaired functioning of tyrosine and tryptophan hydroxylases, and the resultant deficiency of tyrosine- and tryptophan-derived monoamine neurotransmitters in brain. (PMID 3930837 ). |
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| InChI Identifier | InChI=1S/C9H11N5O3/c1-3(15)6(16)4-2-11-7-5(12-4)8(17)14-9(10)13-7/h2-3,6,15-16H,1H3,(H3,10,11,13,14,17)/t3-,6-/m0/s1 |
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