A. Padiglia, G. Floris, S. Longu, M. E. Schininà, J. Z. Pedersen, A. Finazzi Agrò, F. De Angelis, R. Medda
Inhibition of lentil copper/TPQ amine oxidase by the mechanism-based inhibitor derived from tyramine
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,
phydroxyphenylacetaldehyde. The kinetic data
obtained in this study indicate that tyramine represents
a new interesting type of physiological mechanismbased
inhibitor for plant copper amine oxidases.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 385, 04/2004
Pages: 323 - 329
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