Purification and properties of the amine oxidase of pea seedlings

Abstract

A method is described by which the amine oxidase of pea-seedling extracts can be purified up to 300-fold. The purified enzyme preparations catalysed oxidation not only of diamines but also, though less readily, of phenylalkylamines, aliphatic monoamines and of L- and D-lysine. L- and DL-hydroxylysine, DL-diaminopropionic acid, L-diaminobutyric acid, L-ornithine and L histidine were not oxidized. H2O2 was formed during the oxidation of all substrates. Inactivation of the enzyme by H2O2 was confirmed and conditions of this inactivation investigated. The enzyme was inhibited not only by cyanide and semicarbazide, as previously reported, but also by diethyldithiocarbamate, salicylaldoxime and potassium ethyl xanthate. Salicylaldoxime and thiourea were oxidized by the H2O2 formed in the primary reaction. This oxidation of salicyaldoxime was catalysed by peroxidase. It is suggested that one enzyme - plant amine oxidase - catalyses the oxidation of diamines, phenylalkylamines, aliphatic amines and of L-and D-lysine and that this enzyme may be a metalloprotein.