Inhibition of endive (Cichorium endivia L.) polyphenoloxidase by a Carica papaya latex preparation

When endive polyphenoloxidase (PPO) was incubated with a crude papaya latex extract, it rapidly lost its activity. Inactivation was ascribed to thermo stable nonenzymatic factors of low molecular weight. These factors were par tially purified by a two step protocol including gel filtration chromatogra phy on Biogel P2 and ion exchange chromatography using DEAE Sephadex A25. T he PPO-inactivation rate was first order, when either inactivating agent or proton concentration was evaluated. Inactivation could be partially revers ed by CuSO4, which suggested that the inactivating factor(s) bound to the c opper site of the enzyme. On a more rapid time scale than inactivation, pap aya latex extract acted also as a weak noncompetitive PPO inhibitor.