title: Inhibition of human brain dihydropteridine reductase [E.C.1.6.99.10] by the oxidation products of catecholamines, the aminochromes.
abstract: Dihydropteridine reductase from human brain has been purified to homogeneity using a naphthaquinone affinity column followed by chromatography on a 5'-AMP-Sepharose column. Contrary to earlier findings, dopamine (I), noradrenaline (II), and adrenaline (III) do not inhibit this enzyme at concentrations below 200 microM, but their oxidation products, the respective aminochromes (IV, V and VI) are inhibitors. The Ki values for adrenochrome (VI) are reported.
mesh_terms: D001578:Benzopyrans / Q000494:pharmacology*; D001921:Brain / Q000201:enzymology*; D002395:Catecholamines / Q000494:pharmacology*; D002839:Chromans / Q000494:pharmacology*; D004093:Dihydropteridine Reductase / Q000037:antagonists & inhibitors*; D006801:Humans; D066298:In Vitro Techniques; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D010084:Oxidation-Reduction
chemical_list: D001578:Benzopyrans; D002395:Catecholamines; D002839:Chromans; D004093:Dihydropteridine Reductase; D009247:NADH, NADPH Oxidoreductases