摘要：Polyphenol oxidase (PPO) from tea leaves was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. Of the substrates tested, 4-methylcatechol was the best substrate for PPO with a Km value of 127.8 mM. The optimum pH for PPO activity was found to be 6.02. The enzyme showed high activity over a broad pH range of 4.03-7.00. The optimum temperature for PPO activity was 30 °C. The enzyme had more than 70% of the maximum activity between 20-80 °C. Energy of activation (Ea) and Z values were found to be 58.301 kJ/mol ( r2 = 0.961) and 39.68°C ( r2 = 0.965), respectively. Of the inhibitors tested, L-cysteine was the least potent inhibitor.
