Aqueous extracts of seeds of Duranta plumieri were found to be rich in polyphenol oxidase activity. The anion-exchange chromatography of the crude extract on Streamline DEAE resolved the activity into three fractions. The major fraction (77% of the total activity) was further purified by treating it with concanavalin A-agarose in the batch mode. The enzyme preparation eluting with a-methylmannoside showed a single band on SDS-PAGE. The minimum molecular weight corresponded to 14,000 Da. The K-m and V-max of this isoenzyme were found to be 7.1 mM and 73.5 U ml(-1) min(-1), respectively. The k(cat) of this isoenzyme was calculated to be 8235 s(-1). The isoenzyme also showed the phenomenon of latency and the activity could be enhanced by 196% on heating it at 55degreesC for 30 min. (C) 2002 Elsevier Science (USA).