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

Maria Luisa Di Paolo, Michele Lunelli, Monika Fuxreiter, Adelio Rigo, Istvan Simon, Marina Scarpa

Research output: Contribution to journalArticle

4 Citations (Scopus)

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 (k c) 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.

Original languageEnglish
Pages (from-to)1232-1243
Number of pages12
JournalFEBS Journal
Volume278
Issue number8
DOIs
Publication statusPublished - Apr 1 2011

Keywords

  • amine oxidase
  • substrate docking
  • substrate selectivity
  • substrate-dependent catalytic mechanism
  • titratable amino acids

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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