Mechanistic studies on the MPTP inactivation of MAO B

When monoamine oxidase B (MAO B) from rat liver mitochondria was incubated with MPTP, methylamine was formed and MAO B was inactivated. Incubation of 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP+) with MAO B also yielded methylamine and resulted in inactivation of the enzyme. Similar rate consts. for inactivation of MAO B were obtained with 1-methyl-4-phenyl-1,4-dihydropyridine, 3-phenylglutaraldehyde (3-PG), and 2,6-dihydroxy-4-phenyltetrahydropyran, suggesting that bioalkylation of the enzyme occurs outside the active site via a species such as 3-PG.