POLYAMINE OXIDASE BOUND TO CELL-WALLS FROM ZEA-MAYS SEEDLINGS

Some kinetic and physicochemical properties of polyamine oxidase tightly bound to cell walls from Zea mays seedlings, have been examined and compared with those of ionically wall-bound enzyme. Both enzymes showed similar apparent K(m) for spermidine, spermine and O2, respectively, the same substrate specificity and the same sensitivity to specific inhibitors, while thermal stability and energy of activation values were higher for the tightly bound enzyme. Fifty per cent of the latter activity was solubilized after 3 hr incubation of the cell wall fraction with a 0.5% Driselase solution. The enzyme extracted in this way showed the same M(r) as the ionically bound protein, determined by immunoblotting. Despite some apparent differences the ionically bound and the tightly wall-bound polyamine oxidases are probably the same protein.