Mechanism-based inactivators of plant copper/quinone containing amine oxidases.
Copper/quinone amine oxidases contain Cu(II) and the quinone of 2,4,5-trihydroxyphenylalanine (topaquinone; TPQ) as cofactors. TPQ is derived by post-translational modification of a conserved tyrosine residue in the protein chain. Major advances have been made during the last decade toward understanding the structure/function relationships of the active site in Cu/TPQ amine oxidases using specific inhibitors. Mechanism-based inactivators are substrate analogues that bind to the active site of an enzyme being accepted and processed by the normal catalytic mechanism of the enzyme. During the reaction a covalent modification of the enzyme occurs leading to irreversible inactivation. In this review mechanism-based inactivators of plant Cu/TPQ amine oxidases from the pulses lentil (Lens esculenta), pea (Pisum sativum), grass pea (Lathyrus sativus) and sainfoin (Onobrychis viciifolia,) are described. Substrates forming, in aerobiotic and in anaerobiotic conditions, killer products that covalently bound to the quinone cofactor or to a specific amino acid residue of the target enzyme are all reviewed.
Longu
Silvia
S
Department of Applied Sciences in Biosystems, University of Cagliari, Cittadella Universitaria, I-09042 Cagliari, Italy.
Mura
Anna
A
Padiglia
Alessandra
A
Medda
Rosaria
R
Floris
Giovanni
G
D006631:Amine Oxidase (Copper-Containing) / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D010944:Plants / Q000201:enzymology*; D011809:Quinones / Q000378:metabolism*; D014439:Tyramine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011809:Quinones; D006631:Amine Oxidase (Copper-Containing); D014439:Tyramine