Mechanism-based inactivation of dopamine beta-monooxygenase in adrenal chromaffin cells.
Dopamine beta-monoxygenase (DBM, E.C. 1.14.17.1) is an attractive target point for possible modulation of adrenergic activity, and a variety of DBM-targeted pseudosubstrates and inhibitors have been developed in this laboratory and other laboratories. We now demonstrate the efficacy of a DBM-targeted mechanism-based inactivator, as well as enzymatic processing of two alternate DBM substrates, within functional adrenal chromaffin cells. When cultured adrenal medullary chromaffin cells were incubated with the mechanism-based inactivator 1-(4'-hydroxyphenyl)-1-(aminomethyl)-ethene (HOPAME), vesicular DBM activity was markedly decreased. Similarly, the alternate substrates 4'-hydroxyphenyl-2-aminoethyl sulfide and 4'-hydroxyphenyl-2-aminopropyl selenide each undergo uptake and DBM-catalyzed oxygenation within these cells. The simultaneous action of both the mechanism-based inactivator and an alternate substrate within functional chromaffin cells was also demonstrated. These results provide support for a direct mechanistic link between the enzymological properties of DBM-targeted adrenergic agents and their in-vivo pharmacological activities.
May
S W
SW
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332, USA. sheldon.may@chemistry.gatech.edu
Young
F K
FK
Powers
J L
JL
Gill-Woznichak
M M
MM
D000313:Adrenal Medulla / Q000201:enzymology*; D000818:Animals; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000201:enzymology*; D002837:Chromaffin Granules / Q000201:enzymology; D003600:Cytosol / Q000378:metabolism; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D009655:Octopamine / Q000032:analysis; D010636:Phenols / Q000494:pharmacology*; D013343:Styrenes / Q000494:pharmacology*; D013379:Substrate Specificity; D014439:Tyramine / Q000032:analysis
C102377:1-(4'-hydroxyphenyl)-1-(aminomethyl)ethene; D004791:Enzyme Inhibitors; D010636:Phenols; D013343:Styrenes; D009655:Octopamine; D004299:Dopamine beta-Hydroxylase; D014439:Tyramine