Purification and partial characterization of polyphenol oxidase from the flower buds of Lonicera japonica Thunb.

► PPO from flower buds of Lonicera japonica (LjPPO) was purified and characterized ∼49 kDa. ► LjPPO was optimally active at pH 7.5/30 °C and stable at pH 7.0-10.0/below 50 °C. ► LjPPO possess diphenolase activity, rather than monophenolase and triphenolase activities. ► Ascorbic acid was found to be an effective PPO inhibiter. ► Catechol was the appropriate substrate in terms of Vmax/Km values.