Derardja Ala Eddine, Pretzler Matthias, Kampatsikas Ioannis, Radovic Milena, Fabisikova Anna, Zehl Martin, Barkat Malika, Rompel Annette
Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090, Wien, Austria.
Laboratoire Bioqual, INATAA, Université Frères Mentouri Constantine1, Route de Ain El-Bey, 25000, Constantine, Algeria.
Curr Res Food Sci. 2022 Jan 4;5:196-206. doi: 10.1016/j.crfs.2021.12.015. eCollection 2022.
In this study, we investigate the effect of enzymatic browning on the phenolic composition of apricot and . The browning was caused by the recombinant latent apricot polyphenol oxidase (L-PPO). Successful heterologous expression of PPO in yielded substantial amounts of enzyme containing both copper ions in the catalytic active site. The expressed L-PPO was characterized with regard to its molecular mass (56531.3 Da), pH optimum (7.0), activation by SDS, and enzyme kinetics. LC-MS/MS was used to compare the phenolic profiles of brown and non-brown apricots. The browning reactions did significantly decrease total phenolics and antioxidant capacity (measured with DPPH and CUPRAC assays). Catechin, epicatechin, and B-type procyanidins were the individual phenolics most affected by browning, followed by chlorogenic and neochlorogenic acid. These phenolics are most likely the main endogenous substrates of L-PPO, as they were oxidized much faster than the other identified phenolics.
在本研究中，我们研究了酶促褐变对杏子酚类成分的影响。褐变是由重组潜伏性杏子多酚氧化酶（L-PPO）引起的。PPO在[具体生物]中的成功异源表达产生了大量在催化活性位点含有两个铜离子的酶。对表达的L-PPO进行了分子量（56531.3 Da）、最适pH（7.0）、SDS激活以及酶动力学等方面的表征。采用液相色谱-串联质谱法（LC-MS/MS）比较褐色和非褐色杏子的酚类谱图。褐变反应确实显著降低了总酚含量和抗氧化能力（通过DPPH和CUPRAC测定）。儿茶素、表儿茶素和B型原花青素是受褐变影响最大的单个酚类，其次是绿原酸和新绿原酸。这些酚类很可能是L-PPO的主要内源性底物，因为它们比其他已鉴定的酚类氧化得更快。
