Effect of high-pressure carbon dioxide on the aggregation and conformational changes of polyphenol oxidase from apple (Malus domestica) juice
Effect of high-pressure carbon dioxide on the aggregation and conformational changes of polyphenol oxidase from apple (Malus domestica) juice
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DOI：
10.1016/j.ifset.2019.03.001
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发表时间：
2019-06-01
影响因子：
6.6
通讯作者：
Hu, Wanfeng
中科院分区：
文献类型：
--
作者：
Murtaza, Ayesha;Iqbal, Aamir;Hu, Wanfeng
研究了不同状态CO2对苹果汁中多酚氧化酶（PPO）活性及结构修饰的影响。临界和超临界CO2对PPO活性的抑制率分别为64.88%和3.20%。动态光散射分析表明，在临界状态下，两个峰解聚成三个峰，表明小颗粒的解离和聚集。圆二色性分析表明，在临界和超临界CO2状态下，由于α-螺旋含量的损失，二级结构发生了变形。在临界状态下，荧光强度急剧下降至251.3（λ（max）312），表明PPO分子解折叠，从而导致λ（max）的淬灭和蓝移。电泳结果表明，在超临界状态下，大分子聚集体不会进入凝胶。因此，在临界和超临界状态下，HP-CO2处理可以诱导聚集，变形和结构变化，这可能是PPO失活的原因。工业相关性：“多酚氧化（PPO）是引发布朗宁反应和恶化果汁品质的酶”。高压二氧化碳（HP-CO2）技术是一种很有前途的获得高品质低酶活性苹果汁的技术。研究了高压光降解条件下不同状态CO2气体对苹果汁多酚氧化酶活性、聚集、变形和结构变化的影响。这项研究提供的现有结果将有利于食品工业。
This study investigated the effect of different states of CO2 on the activity and structural modification of purified polyphenol oxidase (PPO) from apple juice. CO2 in critical and supercritical states strongly inhibited the PPO activity up to 64.88% and 3.20%, respectively. Dynamic light scattering analysis showed that the two peaks depolymerised into three peaks in the critical state, demonstrating the dissociation and aggregation of small particles. Circular dichroism analysis revealed that the secondary structure deformed because of the loss of alpha-helix contents in the critical and super critical CO2 states. Fluorescence intensity dramatically decreased to 251.3 (lambda(max) 312) in the critical state, showing unfolding of PPO molecules thereby resulting in quenching and blue shifting of lambda(max). Electrophoresis indicated that large molecular aggregates did not run into the gel at supercritical state. Hence, HP-CO2 treatment in critical and super critical states could induce the aggregation, deformation and structural changes which might be the causes of PPO inactivation.Industrial relevance: "Polyphenol oxidation (PPO) is the enzyme that initiates the browning reaction and deteriorates the quality of fruit juices". High pressure carbon dioxide (HP-CO2) technology is a promising technique to obtain high quality apple juices with low enzyme activity. This study analyzed the effects of different states of carbon dioxide gases under HPCD on the activity, aggregation, deformation and structural changes of PPO from apple juice. Available findings provided in this study will benefit the food industry.