CHARACTERIZATION OF MAIZE POLYAMINE OXIDASE

Article abstract of DOI:10.1016/0031-9422(90)85157-B

Some structural and biochemical characteristics of polyamine oxidase (PAO) purified from maize shoots have been examined.The enzyme has only alanine as N-terminal amino acid and its N-terminal sequence shows a significant degree of homology with tryptophan 2-monooxygenase from Pseudomonas syringae pv. savastanoi.The pH optimum for the stability of the native enzyme is 5, similar to that of the barley leaf enzyme.Calorimetric analysis shows a single two-state transition at pH 6 with T_m 49.8 deg.At pH 5 the thermal stability is increased by more than 14 deg.Amine oxidation products, Δ¹-pyrroline and diazabicyclononane, are competitive inhibitors of PAO activity (apparent K_i = 400 and 100 μM respectively).Moreover these compounds improve the thermal stability of the enzyme.N¹-Acetylspermine, which is a good substrate for mammalian PAO, acts as a non-competitive inhibitor for the plant enzyme.