Purification by affinity chromatography and characterization of porcine liver cytoplasmic polyamine oxidase

1. Polyamine oxidase was purified from the soluble fraction of porcine liver by more than 70,000-fold to electrophoretic homogeneity using N8-acetylspermidine-Sepharose 4B affinity chromatography. 2. The molecular weight and isoelectric point of this enzyme were 62,000 and pH 4.5, respectively. 3. Optimal pH for the catalytic activity was close to 10.0. 4. The enzyme activity was enhanced by 5 mM dithiothreitol or 5 mM benzaldehyde. 5. Preferential substrates for this cytoplasmic PAO were N1-acetylspermine, N1-acetylspermidine and spermine. 6. Spermidine was not virtually the substrate for this enzyme. 7. The present results suggested the physiological roles of cytoplasmic PAO, being coupled with the reaction of spermidine/spermine N1-acetyltransferase, in recycling the cellular polyamines to putrescine.