title: Synthesis of several 2-substituted 3-(p-hydroxyphenyl)-1-propenes and their characterization as mechanism-based inhibitors of dopamine beta-hydroxylase.
abstract: Three substrate analogs of dopamine beta-hydroxylase, viz. 2-X-3-(p-hydroxyphenyl)-1- propenes (where X = Br, Cl, H), have been synthesized, and all behave as substrates requiring O2 and ascorbate for the enzyme-catalyzed hydroxylation reaction. The products have been characterized by mass spectrometry as the respective 2-X-3-hydroxy-3-(p-hydroxyphenyl)-1- propenes . The relative kcat values for these compounds at pH 5.5, 0.25 mM O2 are 49 min-1 (2-H), 8.6 min-1 (2-Cl), and 7.0 min-1 (2-Br). All three compounds have the characteristics of mechanism-based inhibitors of dopamine beta-hydroxylase since incubation of enzyme with these compounds under turnover conditions leads to a time-dependent loss of activity. The kinact values at pH 5.5, 0.25 mM O2 are 0.08, 0.20, and 0.51 min-1, respectively, for the 2-Br-, 2-Cl-, and 2-H-substituted analogs. No reactivation was observed after exhaustive dialysis of enzyme inactivated by 2-Br-3-(p-hydroxyphenyl)-1-propene, suggesting irreversible inactivation of dopamine beta-hydroxylase.
mesh_terms: D000313:Adrenal Medulla / Q000201:enzymology; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors*; D007700:Kinetics; D013058:Mass Spectrometry; D010100:Oxygen / Q000378:metabolism; D010636:Phenols / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: C040825:2-bromo-(4-hydroxyphenyl)-1-propene; D010636:Phenols; C041473:2-chloro-3-(4-hydroxyphenyl)-1-propene; C041474:3-(4-hydroxyphenyl)-1-propane; D004299:Dopamine beta-Hydroxylase; D001205:Ascorbic Acid; D010100:Oxygen