Active site residue involvement in monoamine or diamine oxidation catalysed by pea seedling amine oxidase

Abstract

The structures of copper amine oxidases from various sources show good similarity, suggesting similar catalytic mechanisms for all members of this enzyme family. However, the optimal substrates for each member differ, depending on the source of the enzyme and its location. The structural factors underlying substrate selectivity still remain to be discovered. With this in view, we examined the kinetic behaviour of pea seedling amine oxidase with cadaverine and hexylamine, the first bearing two, and the second only one, positively charged amino group. The dependence of Km and catalytic constant (kc) values on pH, ionic strength and temperature indicates that binding of the monoamine is driven by hydrophobic interactions. Instead, binding of the diamine is strongly facilitated by electrostatic factors, controlled by polar side‐chains and two titratable residues present in the active site. The position of the docked substrate is also essential for the participation of titratable amino acid residues in the following catalytic steps. A new mechanistic model explaining the substrate‐dependent kinetics of the reaction is discussed.

A molecular model of human Lysyl Oxidase (LOX) with optimal copper orientation in the catalytic cavity for induced fit docking studies with potential modulators

“…Similarly, the active cavity of the modelled LOX structure was observed to be anionic. Further, the proton abstraction is usually catalyzed by aspartic acid in case of all amine oxidases [26, 27]. In this study, the IFD results for LOX with pseudo substrate DAP and all the inhibitors also strongly infer Asp residues as major contributors of hydrogen bonding interactions.…”

Genome-Wide Identification, Characterization, and Expression Analysis of the Copper-Containing Amine Oxidase Gene Family in Mangrove Kandelia obovata

“…However, in Arabidopsis, both Put and Spd can be catalyzed by CuAO [4,6]. The homodimeric nature of plant CuAOs is characterized by the presence of a copper ion and a 2, 4, 5-trihydroxyphenylalanine quinone cofactor (TPQ) site within each subunit [8,9]. Nevertheless, it has been revealed by Planas-Portell et al [6] that the CuAOs of Arabidopsis (AtCuAO1-AtCuAO3) are capable of utilizing both Put and Spd as substrates.…”