The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase
The effect of citric acid on the activity, thermodynamics and conformation of mushroom polyphenoloxidase
复制标题
柠檬酸对蘑菇多酚氧化酶活性、热力学和构象的影响
DOI：
10.1016/j.foodchem.2013.02.028
复制
发表时间：
2013-09-15
期刊：
影响因子：
8.8
通讯作者：
Liang, Rui-hong
中科院分区：
文献类型：
--
作者：
Liu, Wei;Zou, Li-qiang;Liang, Rui-hong
柠檬酸对多酚氧化酶（PPO）的热力学和构象的影响研究较少。研究了柠檬酸（1-60 mM）诱导蘑菇多酚氧化酶（PPO）活性、热力学和构象的变化及其相互关系。结果表明，随着柠檬酸浓度的增加，PPO的活性逐渐降低，直至失活; PPO失活速率常数k增大，活化能E-a和热力学参数Δ G、Δ H、Δ S减小，表明PPO的热敏性、稳定性和非共价键数均降低。构象逐渐展开，表现为α-螺旋含量减少，β-折叠增加，芳香族氨基酸残基暴露。此外，还得到了相对活性Δ H与α-螺旋含量的两个线性关系。这表明活性和热力学的变化可能与构象的解折叠有关。(C)2013爱思唯尔有限公司保留所有权利。
Few reports have focused on the effect of citric acid on thermodynamics and conformation of polyphenoloxidase (PPO). In this study, variations on activity, thermodynamics and conformation of mushroom PPO induced by citric acid (1-60 mM) and relationships among these were investigated. It showed that with the increasing concentration of citric acid, the activity of PPO decreased gradually to an inactivity condition; inactivation rate constant (k) of PPO increased and the activation energy (E-a) as well as thermodynamic parameters (Delta G, Delta H, Delta S) decreased, which indicated that the thermosensitivity, stability and number of non-covalent bonds of PPO decreased. The conformation was gradually unfolded, which was reflected in the decrease of alpha-helix contents, increase of beta-sheet and exposure of aromatic amino acid residuals. Moreover, two linear relationships of relative activities, enthalpies (Delta H) against alpha-helix contents were obtained. It indicated that changes of activity and thermodynamics might correlate to the unfolding of conformation. (C) 2013 Elsevier Ltd. All rights reserved.