Zhou Lei, Liu Wei, Zou Liqiang, Xiong Zhiqiang, Hu Xiuting, Chen Jun
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Food Chem. 2017 Jan 1;214:423-431. doi: 10.1016/j.foodchem.2016.07.041. Epub 2016 Jul 6.
This study investigated changes in the activity, conformation and microstructure of mushroom polyphenoloxidase (PPO) subjected to thermal treatment. The inactivation of PPO can be achieved by high temperature-short time or mild temperature-long time treatment. Circular dichroism and fluorescence spectra suggested that heating process induced the rearrangement of secondary structure and the disruption of tertiary structure. Red shifts of fluorescence spectra showed positive correlations with the inactivation rate of PPO. There were significant differences in the conformation and molecular microstructure among PPO samples with the same relative activity, which were obtained by treating PPO at 45, 55 and 65°C for different times. In summary, PPO molecules were deformed at mild temperature, while higher temperature induced the formation of large aggregates. PPO with the same relative activity might exist in different forms.
本研究调查了经热处理的蘑菇多酚氧化酶（PPO）的活性、构象和微观结构的变化。通过高温短时间或温和温度长时间处理可实现PPO的失活。圆二色光谱和荧光光谱表明，加热过程诱导了二级结构的重排和三级结构的破坏。荧光光谱的红移与PPO的失活率呈正相关。在45、55和65°C下对PPO进行不同时间处理后获得的具有相同相对活性的PPO样品，其构象和分子微观结构存在显著差异。总之，PPO分子在温和温度下发生变形，而较高温度诱导形成大聚集体。具有相同相对活性的PPO可能以不同形式存在。
