title: Inhibition of lentil copper/TPQ amine oxidase by the mechanism-based inhibitor derived from tyramine.
abstract: Copper amine oxidase from lentil (Lens esculenta) seedlings was shown to catalyze the oxidative deamination of tyramine and three similar aromatic monoamines, benzylamine, phenylethylamine and 4-methoxyphenylethylamine. Tyramine, an important plant intermediate, was found to be both a substrate and an irreversible inhibitor of the enzyme whereas the other amines were not inhibitory. In the course of tyramine oxidation the enzyme gradually became inactivated with the concomitant appearance of a new absorption at 560 nm due to the formation of a stable adduct. Inactivation took place only in the presence of oxygen and was probably due to the reaction of the enzyme with the oxidation product of tyramine, p-hydroxyphenylacetaldehyde. The kinetic data obtained in this study indicate that tyramine represents a new interesting type of physiological mechanism-based inhibitor for plant copper amine oxidases.
authors.affiliation: Department of Applied Sciences in Biosystems, University of Cagliari, 1-09042 Monserrato, CA, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Padiglia
authors.forename: Giovanni
authors.initials: G
authors.lastname: Floris
authors.forename: Silvia
authors.initials: S
authors.lastname: Longu
authors.forename: M Eugenia
authors.initials: ME
authors.lastname: Schininà
authors.forename: Jens Z
authors.initials: JZ
authors.lastname: Pedersen
authors.forename: Alessandro
authors.initials: A
authors.lastname: Finazzi Agrò
authors.forename: Francesco
authors.initials: F
authors.lastname: De Angelis
authors.forename: Rosaria
authors.initials: R
authors.lastname: Medda
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000302:isolation & purification; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000302:isolation & purification; D027806:Lens Plant / Q000201:enzymology*; D010936:Plant Extracts / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D036226:Seedlings; D014439:Tyramine / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: C086758:2,4,5-trihydroxyphenylalanine quinone; D004791:Enzyme Inhibitors; D010936:Plant Extracts; D004295:Dihydroxyphenylalanine; C067626:6-hydroxydopa quinone; D006631:Amine Oxidase (Copper-Containing); D014439:Tyramine