Inhibition of pig liver and Zea mays L. polyamine oxidase: A comparative study

Polyamine oxidase (PAO) is involved in polyamine metabolism and production of hydrogen peroxide in animal and plants, thus representing a key system i n development and programmed cell death. In the present study, the inhibito ry effect of amiloride, p-aminobenzamidine, clonidine, 4',6-diamidino-2-phe nyl-indole (I)API), gabexate mesylate, guazatine, and N,N'-bis(2,3-butadien yl)-1,4-butane-diamine (MDL72527) on the catalytic activity of pig liver an d Zea mays L, PAO, Lens culinaris L. and Pisum sativum L. and swine kidney copper amine oxidase, bovine trypsin, as well as neuronal constitutive nitr ic oxide synthase (NOS-I) was investigated. Moreover, agmatine and N-3-pren ylagmatine (G3) were observed to inhibit pig liver and Zea mays L. PAO, bov ine trypsin, and NOS-I action, but were substrates for Lens culinaris L., P isum sativum L. and swine kidney copper amine oxidase. Guazatine and G3 inh ibited selectively Zea mays L. PAO with K-i values of 7.5x10(-9) M and 1.5x 10(-8) M, respectively (at pH 6.5 and 25.0 degreesC). As a whole, the data reported here represent examples of enzyme cross-inhibition, and appear to be relevant in view of the use of cationic L-arginine-and imidazole-based c ompounds as drugs.