High-performance liquid chromatographic methods for the quantification of tetrahydrobiopterin biosynthetic enzymes.
Tetrahydrobiopterin is a cofactor in hydroxylation reactions, including phenylalanine 4-monooxygenase, tyrosine 3-monooxygenase, tryptophan 5-monooxygenase, alkyl glycol ether monooxygenase and nitric oxide synthase. Determination of its biosynthesis is carried out to diagnose inherited diseases leading to partial defects in tetrahydrobiopterin synthesis. In addition, tetrahydrobiopterin synthesis is induced by proinflammatory cytokines, and intracellular levels of tetrahydro-biopterin in many cases limit the activity of tetrahydrobiopterin-dependent reactions, such as nitric oxide synthase in intact cells. Biosynthesis of tetrahydrobiopterin from guanosine 5'-triphosphate (GTP) requires the action of three enzymes, GTP-cyclohydrolase I (E.C. 3.5.4.16), 6-pyruvoyl tetrahydropterin synthase (EC, 4.6.1.10) and sepiapterin reductase (E.C. 1.1.1.153). Methods for quantification of biopterin and related pteridines in biological matrices by HPLC and application of these for determining the activity of the three tetrahydrobiopterin biosynthetic enzymes are reviewed in this article.
Institut für Medizinische Chemie and Piechemic, Universität Innsbuck, Austria.
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Werner-Felmayer
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D000429:Alcohol Oxidoreductases / Q000032:analysis*; D000975:Antioxidants / Q000378:metabolism*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000096:biosynthesis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006136:GTP Cyclohydrolase / Q000032:analysis*; D019761:Phosphorus-Oxygen Lyases
D000975:Antioxidants; D001708:Biopterins; D000429:Alcohol Oxidoreductases; C022630:sepiapterin reductase; D006136:GTP Cyclohydrolase; D019761:Phosphorus-Oxygen Lyases; C043497:6-pyruvoyltetrahydropterin synthase; C003402:sapropterin