ACTIVATION OF PLATELET MONO-AMINE OXIDASE BY PLASMA IN THE HUMAN

A pronounced activation of platelet monoamine oxidase (MAO) by human plasma has been observed. The activation was substrate selective, since serotonin, p-tyramine, dopamine and benzylamine were much more effective than β-phenylethylamine or tryptamine. The activator(s) in the plasma was heat stable but labile to acid hydrolysis and treatment with lipase and protease. The plasma was also found to be capable of activating partially purified MAO obtained from rat liver mitochondria. Phospholipids such as phosphatidylethanolamine were shown to activate MAO. © 1979.