Molecular Pharmacology, Vol 13, 1005-1013, Copyright © 1977 by the American Society for Pharmacology and Experimental Therapeutics

The Pseudoirreversible Inhibition of Monoamine Oxidase by Allylamine

¹ Department of Pharmacology, Harvard Medical School, Boston, Massachusetts 02115

Allylamine was shown to inhibit flavin-linked monoamine oxidase in a pseudoirreversible manner. The enzyme was irreversibly inhibited with incorporation of radioactivity from [¹⁴C]allylamine. Inhibition and incorporation of radioactivity were time-dependent, and the radioactivity and inhibition persisted during dialysis and gel filtration. Enzymatic turnover of allylamine preceded the inactivation step. Reaction of the allylamine-inactivated enzyme with benzylamine resulted in the formation of 3-benzylaminopropionaldehyde. Simultaneously with inactivation, the ultraviolet spectrum of the holoenzyme changed to one indicative of the reduced form of the coenzyme. In the presence of a substrate, benzylamine, the ultraviolet spectrum of the enzyme reverted to normal, the radioactivity was removed, and activity was restored. A mechanism for the inactivation and reactivation by benzylamine is presented.