Abstract: Polyphenol oxidase（PPO）from Agaricus bisporus was extracted and purified by salting-out，DEAE-Cellulose-52 anion exchange chromatography and Sephadex G-100 gel column chromatography. The protein yield and PPO activity were analyzed during purification. The final purification fold，specific activity and protein yield were 103.2，566.57 U · mg^-1 and 0.47%，respectively. The SDS-PAGE analysis showed that the PPO was a single protein band with a molecular weight of about 25.5 kD. The observation by scanning probe microscope showed that the PPO from Agaricus bisporus was ellipsoidal，with a diameter of about 8–12 nm.

Key words: Agaricus bisporus, polyphenol oxidase, purification, molecular shape