OXIDATION OF ACETYLPOLYAMINES BY MAIZE-POLYAMINE OXIDASE

The oxidation of acetylpolyamines by cell wall polyamine oxidase from maize shoots was investigated. The purified enzyme catalysed the oxida tion of N-1-acetylspermine, N-8-acetylspermidine, and N-8-acetylspermi dine at the same optimal pH (6.5), but with lower relative velocities and higher K-m than those found for spermine and spermidine oxidation. The enzyme cleaved N-1-acetylspermidine and N-8-acetylspermidine, at the same positions as in spermine and spermidine oxidation, with the p roduction of H2O2, 1,3-diaminopropane and the corresponding aminoaldeh ydes. Polyamine oxidase was quickly inactivated by catalysis, and the aminoaldehyde derived from N-1-acetylspermine behaved as a competitive inhibitor of the enzyme (K-i=20 mu M). These findings suggest that ce ll wall polyamine oxidase from maize shoots does not effect the interc onversion pathway of acetylpolyamines found in vertebrates. Copyright (C) 1996 Elsevier Science Ltd.