Abstract：The characterics of luffa polyphenol oxidase were studied with spectrophotometry using catechol as substrate.The results showed that the optimum temperature of luffa polyphenol oxidase was 20 ℃,and the optimum pH was 6.8.The enzyme activity was higher when the reacting system was at 15～25 ℃ or the pH value was between 6.4～7.2.The experiment of heat stability of luffa PPO indicated that the activity of PPO remained 4.81 % in 100 ℃ by 3 min,while it reduced to 38.08 % in 60 ℃ by 3 min.The dynamics research proved that the Km=0.067 56 mol·L-1,Vmax=0.238 5 A410·min-1 in Michaelis.Menten equation when catechol was substrate.The single inhibitor VC and sodium thiosulfate had inhibiting effect on polyphenol oxidase,but had different effective inhibiting concentration.The effective concentration of ascorbic acid was 50.0 mg·L-1,which was the lowest in the 3 inhibitors,sodium thiosulfate was 100 mg·L-1.Critic acid was the most ineffective inhibitor.
