Prokaryotic expression and purification of Camellia sinensis polyphenol oxidase

BACKGROUND: Polyphenol oxidase (PPO) causes the postharvest loss of fruits and vegetables but is also a key factor in the quality development of tea. However, there are no reports on engineered active plant PPO purified from prokaryotic cells. RESULTS: In this study the ppo gene of about 1800 bp from Camellia sinensis cv. Yihongzao was successfully cloned and expressed in Escherichia coli. The PPOs purified from both the soluble fraction and the inclusion bodies showed activity. In addition, 1.0 × 10^?7 mol L^?1 Cu²⁺ and acidic conditions were found to be favourable for the engineered PPO catalysis of catechol oxidation. CONCLUSION: This paper represents the first report on C. sinensis ppo expression in E. coli and engineered active PPO purification. The results of the study provide a basis for the large‐scale preparation and application of PPO. Copyright © 2010 Society of Chemical Industry