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

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journal contribution
posted on 16.08.2017 by Ala eddine Derardja, Matthias Pretzler, Ioannis Kampatsikas, Malika Barkat, Annette Rompel
Polyphenol oxidase from apricot (Prunus armeniaca) (PaPPO) was purified in its latent form (L-PaPPO), and the molecular weight was determined to be 63 kDa by SDS-PAGE. L-PaPPO was activated in the presence of substrate at low pH. The activity was enhanced by CuSO4 and low concentrations (≤ 2 mM) of SDS. PaPPO 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 (KM = 2.0 mM) and chlorogenic acid (KM = 2.7 mM). L-PaPPO was found to be spontaneously activated during storage at 4 °C, creating a new band at 38 kDa representing the activated form (A-PaPPO). The mass of A-PaPPO was determined by mass spectrometry as 37 455.6 Da (Asp102 → Leu429). Both L-PaPPO and A-PaPPO were identified as polyphenol oxidase corresponding to the known PaPPO sequence (UniProt O81103) by means of peptide mass fingerprinting.