Purification and Characterization of Latent Polyphenol Oxidase from Apricot ( Prunus armeniaca L.)

High Resolution Image Download MS PowerPoint Slide Polyphenol oxidase from apricot ( Prunus armeniaca ) ( Pa PPO) was purified in its latent form (L- Pa PPO), and the molecular weight was determined to be 63 kDa by SDS-PAGE. L- Pa PPO was activated in the presence of substrate at low pH. The activity was enhanced by CuSO 4 and low concentrations (≤ 2 mM) of SDS. Pa PPO has its pH and temperature optimum at pH 4.5 and 45 °C for catechol as substrate. It showed diphenolase activity and highest affinity toward 4-methylcatechol ( K M = 2.0 mM) and chlorogenic acid ( K M = 2.7 mM). L- Pa PPO was found to be spontaneously activated during storage at 4 °C, creating a new band at 38 kDa representing the activated form (A- Pa PPO). The mass of A- Pa PPO was determined by mass spectrometry as 37 455.6 Da (Asp102 → Leu429). Both L- Pa PPO and A- Pa PPO were identified as polyphenol oxidase corresponding to the known Pa PPO sequence (UniProt O81103 ) by means of peptide mass fingerprinting.