Herbert Tabor

Abstract: Numerous investigators have studied monoamine oxidase since it was first described (2) in 1928. The literature has recently been reviewed by Blaschko (3) and Zeller (4). Monoamine oxidase has usually been considered as a single enzyme (5), but some authors (Werle and Roewer (6) and Alles and Heegaard (7)) have presented evidence indicating that these preparations contained more than one type of amine oxidase activity. All of these studies, however, have been carried out with relatively crude preparations, since monoamine oxidase is associated with particulate material and has resisted efforts to purify it. Although many tissues were found to contain this activity, liver preparations have been most commonly used. Amine oxidase activity has been reported to be present in dog blood by Werle and Roewer (6), but has usually been considered to be absent in the blood of other species (3). Although Hirsch (8) reported the oxidation of spermine and spermidine by beef and sheep serum, no significant activity Tvas observed with those monoamines and diamines tested. In the present work a soluble amine oxidase has been purified 150to 200fold from steer plasma; the enzyme oxidatively deaminates a variety of amines with the stoichiometric formation of the corresponding aldehydes, ammonia, and hydrogen peroxide. The substrate and inhibitor specificities of this enzyme differ markedly from those described for the liver preparations.