Competitive inhibition of Lens culinaris L. copper amine oxidase by amiloride, p-aminobenzamidine, clonidine, 4',6-diamidino-2-phenylindole and gabexate mesylate: A comparative study

The competitive inhibition of Lens culinaris L. copper amine oxidase by amiloride (K(i) = 4.1 x 10^-4M), p-aminobenzamidine (K(i) = 6.0 x 10^-4M), clonidine (K(i) = 5.0 x 10^-4M), 4',6-diamidino-2-phenylindole (DAPI; K(i) = 1.9 x 10^-5M) and gabexate mesylate (K(i) = 2.5 x 10^-4M) has been investigated, at pH 7.0 and 25°C. The affinity of p-aminobenzamidine, clonidine and DAPI for plant and mammalian copper amine oxidase is closely similar. However, values of K(i) for amiloride and gabexate mesylate binding to swine kidney copper amine oxidase are lower than those observed for inhibitor binding to Lens culinaris L. copper amine oxidase. Thus, amiloride and gabexate mesylate may represent useful model compounds for the development of selective inhibitors of mammalian copper amine oxidase, which may be important in view of the potential use of plant copper amine oxidase as drugs.