Enzymologic properties of polyphenol oxidase of Lactuca sativa var.angustata

The kinetic property of polyphenol oxidase(PPO)in Lactuca sativa var. angustata was analyzed. The result showed that,by using the catechol as the substrate,the most suitable pH and temperature for this enzyme was at 7. 4 and 30℃,respectively,and it would be rapid inactivated if the temperature went above 70℃. The kinetic equation was v=518. 96[S]/(0. 0166+[S]),and VC,sodium D-isoascorbate,NaHSO3,L-Cys could completely inhibit PPO activity. Saturated NaCl,sugar(10%),SDS and EDTA-Na2 could remarkably inhibite PPO activity. This enzyme could catalyze the oxidization of catechol and pyrogallic acid,and had higher affinity to catechol.