Abstract: In this study,the soluble （sPPO） and membrane bound （mPPO） polyphenol oxidases were prepared from black beauty potatoes and the enzymatic properties were comparatively investigated,aiming to effectively control enzymatic browning during potatoes processing.Results showed that the maximum absorption wavelengths of s P-PO and mPPO were 403 nm and 406 nm,respectively.The optimum reaction temperatures of sPPO and mPPO were 25℃and 30℃respectively with the same optimum reaction pH value of 7.The sPPO and mPPO showed no activity using chlorogenic acid or resorcinol as substrates.Michaelis constants （K_m） of sPPO and mPPO were 39.423 mmol/L and 35.291 mmol/L with catechol as substrate,and the maximum enzyme speeds (V_max) were 0.019 mmol·L^-1·min^-1and 0.290 mmol·L^-1·min^-1,respectively.When employing pyrogallic acid as substrate,the K_m and V_maxvalues of sPPO/mPPO were 205.896/205.067 mmol/L and 0.008/22.321 mmol·L^-1·min^-1,respectively Besides,the sodium sulfite and ascorbic acid could significantly restrain the activities of sPPO and m PPO,and phytic acid,oxalic acid,citric acid,and EDTA also showed different inhibitory degrees on sPPO and m PPO activities These results demonstrated that the enzymatic properties of m PPO and sPPO presented great differences,m PPO showed obviously higher enzymatic activities than sPPO.Therefore,the effects of m PPO on enzymatic browning of black beauty potatoes should be emphasized during potatoes processing.