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 language | English (US) |
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Pages (from-to) | 13-29 |
Number of pages | 17 |
Journal | Toxicology |
Volume | 44 |
Issue number | 1 |
DOIs | |
State | Published - Apr 1987 |
Externally published | Yes |
Keywords
- Allylamine
- Aorta
- Benzylamine oxidase
- Covalent binding
- Mitochondria
- Monoamine oxidase
- Myocardium
- Phospholipases
- Radiological binding
ASJC Scopus subject areas
- Toxicology