Radioenzymatic assay of catecholamines: reversal of aluminium inhibition of enzymatic O-methylation by desferrioxamine.
Alumina is commonly used for the purification and concentration of catecholamines in biological specimens before analysis. Acid eluates of alumina, found to contain high concentrations of Al3+, interfered with O-methylation but not with N-methylation. The chemistry of the catecholamines, supported by kinetic studies, suggest that complex formation between aluminium and the substrate account for the observed inhibition of O-methylation. The addition of desferrioxamine, a metal-chelating agent, to the reaction mixture reversed this inhibition and, by allowing a preliminary alumina extraction, permits the measurement of low concentrations of catecholamines in biological samples.
D000535:Aluminum / Q000494:pharmacology; D065098:Catechol O-Methyltransferase Inhibitors; D002395:Catecholamines / Q000032:analysis*; D003676:Deferoxamine / Q000494:pharmacology; D006801:Humans; D008745:Methylation; D010625:Phenylethanolamine N-Methyltransferase / Q000037:antagonists & inhibitors
D065098:Catechol O-Methyltransferase Inhibitors; D002395:Catecholamines; D000535:Aluminum; D010625:Phenylethanolamine N-Methyltransferase; D003676:Deferoxamine