Purification of potato polyphenol oxidase (PPO) by partitioning in aqueous two-phase system

The aim of this work is to extract and purify potato polyphenol oxidase (PPO) from the potato tuber (Solanum tuberosum) using aqueous two-phase system (ATPS). The PPO was extracted by partitioning in ATPS composed of polyethylene glycol (PEG) and phosphate. Effect of phase composition, molecular weight of PEG and pH of the system on enzyme partitioning and selective enrichment was studied. The optimum system was found at pH 7.0 containing 5% PEG-8000 and 28.5% phosphate, with Ka of 32.3, purification factor of 15.7 and a 97.0% yield of enzyme activity in the top phase.