Binding of [14C] allylamine to isolated mitochondria from rat heart and aorta

Robert M. Hysmith, Paul J. Boor

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

This study demonstrates specific and saturable binding [14C] allylamine to mitochondria derived from rat aorta and heart. Specific binding is linear with respect to mitochondrial concentration and has a pH optimum of 7.0. Saturation isotherms reveal anomolus kinetics of specific binding on heart mitochondria with a high affinity site (KD 16 nM) and a lower affinity site (KD 80 nM); Scatchard plots have a common intercept. Exhaustive flow dialysis in the presence of SDS demonstrates that as much as 23.5% of bound radioactive moieties in aorta mitochondria are covalently bound, and as much as 42.6% are covalently bound in heart mitochondria. Hydrolysis of heart mitochondria with phospholipase C markedly enhances saturation of [14C]allylamine, and greatly increases the quantity of covalently bound radioactive ligand. Phospholipase C hydrolysis of heart mitochondria increased monoamine oxidase B activities and unmasked a small amount of benzylamine oxidase activity, whereas hydrolysis of mitochondria with phospholipases A2 and D diminish MAO-B activity. The monoamine oxidase B inhibitor, deprenyl, significantly reduced both specific and covalent binding of the 14C-activity from [14C]allylamine to phospholipase hydrolyzed mitochondria. The benzylamine oxidase inhibitor, phenelzine, significantly decreased specific binding but had no effect on the degree of covalent binding of [14C]allylamine to phospholipase C hydrolyzed mitochondria. The benzylamine oxidase inhibitor, semicarbazide, had no effect in inhibiting [14C]allylamine binding. Covalent binding of 14-moiety from [14C]allylamine to mitochondria - which express specific sites for the [14C]allylamine-and inhibition of binding by monoamine oxidase inhibitors, suggest the formation of highly reactive intermediates.

Original languageEnglish (US)
Pages (from-to)13-29
Number of pages17
JournalToxicology
Volume44
Issue number1
DOIs
StatePublished - Apr 1987

Keywords

  • Allylamine
  • Aorta
  • Benzylamine oxidase
  • Covalent binding
  • Mitochondria
  • Monoamine oxidase
  • Myocardium
  • Phospholipases
  • Radiological binding

ASJC Scopus subject areas

  • Toxicology

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