Kinetic properties of novel amine oxidase isolated from sainfoin (Onobrychis viciifolia) were compared to those of typical plant amine oxidase (EC 1.4.3.6) from lentil (Lens culinaris). The amine oxidase from sainfoin was active toward substrates, such as 1,5‐diaminopentane (cadaverine) with Km of 0.09 mM and 1,4‐diaminobutane (putrescine) with Km of 0.24 mM. The maximum rate of oxidation for cadaverine at saturating concentration was 2.7 fold higher than that of putrescine. The amine oxidase from lentil had the maximum rate for putrescine comparable to the rate of sainfoin amine oxidase with the same substrate. Both amine oxidases, like other plant Cu‐amine oxidases, were inhibited by substrate analogs (1,5‐diamino‐3‐pentanone, 1,4‐diamino‐2‐butanone and aminoguanidine), Cu2+ chelating agents (diethyltriamine, 1,10‐phenanthroline, 8‐hydroxyquinoline, 2,2′‐bipyridyl, imidazole, sodium cyanide and sodium azide), some alkaloids (L‐lobeline and cinchonine), some lathyrogens (β‐aminopropionitrile and aminoacetonitrile) and other inhibitors (benzamide oxime, acetone oxime, hydroxylamine and pargyline). Tested by Ouchterlony's double diffusion in agarose gel, polyclonal antibodies against the amine oxidase from sainfoin, pea and grass pea cross‐reacted with amine oxidases from several other Fabaceae and from barley (Hordeum vulgare) of Poaceae, while amine oxidase from the filamentous fungus Aspergillus niger did not cross‐react at all. However, using Western blotting after SDS‐PAGE with rabbit polyclonal antibodies against the amine oxidase from Aspergillus niger, some degree of similarity of plant amine oxidases from sainfoin, pea, field pea, grass pea, fenugreek, common melilot, white sweetclover and Vicia panonica with the A. niger amine oxidase was confirmed.
