Derardja Ala Eddine, Pretzler Matthias, Kampatsikas Ioannis, Barkat Malika, Rompel Annette
Universität Wien , Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria.
Laboratoire Bioqual, INATAA, Université des Frères Mentouri , Constantine 1, Route de Ain El-Bey, 25000 Constantine, Algeria.
J Agric Food Chem. 2017 Sep 20;65(37):8203-8212. doi: 10.1021/acs.jafc.7b03210. Epub 2017 Sep 8.
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 CuSO 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 (K = 2.0 mM) and chlorogenic acid (K = 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.
从杏（Prunus armeniaca）中纯化得到的多酚氧化酶（PaPPO）以其无活性形式（L-PaPPO）存在，通过SDS-PAGE测定其分子量为63 kDa。L-PaPPO在低pH值且有底物存在的情况下被激活。硫酸铜和低浓度（≤2 mM）的SDS可增强其活性。以邻苯二酚为底物时，PaPPO的最适pH值和温度分别为4.5和45°C。它表现出双酚酶活性，对4-甲基邻苯二酚（K = 2.0 mM）和绿原酸（K = 2.7 mM）具有最高亲和力。发现L-PaPPO在4°C储存期间会自发激活，产生一条代表激活形式（A-PaPPO）的38 kDa新条带。通过质谱法测定A-PaPPO的质量为37455.6 Da（Asp102 → Leu429）。通过肽质量指纹图谱法，L-PaPPO和A-PaPPO均被鉴定为与已知PaPPO序列（UniProt O81103）对应的多酚氧化酶。
