Activity, Electrophoretic Characteristics and Heat Inactivation of Polyphenoloxidases from Apples, Avocados, Grapes, Pears and Plums
Activity, Electrophoretic Characteristics and Heat Inactivation of Polyphenoloxidases from Apples, Avocados, Grapes, Pears and Plums
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DOI：
10.1006/fstl.1997.0302
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
C. Weemaes;L. Ludikhuyze;I. V. Broeck;M. Hendrickx;P. Tobback
中科院分区：
文献类型：
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作者：
C. Weemaes;L. Ludikhuyze;I. V. Broeck;M. Hendrickx;P. Tobback
摘要 从苹果、鳄梨、葡萄、梨和李子中提取多酚氧化酶（PPO）。鳄梨中的 PPO 活性高于李子，李子中的 PPO 活性高于苹果、葡萄和梨。对于所有研究案例，酶活性在中性 pH 值（pH 6-7）附近达到最大。苹果、梨和李子的 PPO 分子量似乎超过 750 kDa，这可能是由于提取过程中发生聚集现象所致。对于鳄梨，除了大聚集体（MW > 750 kDa）之外，还检测到了两个较小的 PPO 分子，MW 分别为 58.5 和 66.5 kDa。李子 PPO 似乎至少有两种同工酶（pI 4.8 和 5.2）。对于鳄梨 PPO，pI 值分别为 4.6 和 4.7。对于所有研究的 PPO 来说，热失活均遵循一级衰减。除苹果和梨的PPO外，在研究的温度域内，小数还原时间与失活温度之间呈对数线性关系。苹果和梨 PPO 的“断点”分别为 72.5 和 75 °C。高于和低于这些温度时，注意到小数还原时间和失活温度之间的对数线性关系。 PPO 的耐热性似乎取决于其来源。在研究的多酚氧化酶中，葡萄 PPO 对热最敏感。
Abstract Polyphenoloxidases (PPO) were extracted from apples, avocados, grapes, pears and plums. In avocados, higher PPO activity was observed than in plums, which showed higher PPO activity than apples, grapes and pears. For all cases studied, enzyme activity was maximal around neutral pH (pH 6–7). Apple, pear and plum PPO appeared to have a molecular weight exceeding 750 kDa, which might be due to aggregation phenomena taking place during extraction. For avocado, in addition to a large aggregate (MW > 750 kDa), two smaller PPO molecules with a MW of 58.5 and 66.5 kDa were detected. Plum PPO seemed to have at least two isoenzymes (pI 4.8 and 5.2). In the case of avocado PPO, pI values equalled 4.6 and 4.7. Thermal inactivation followed first-order decay for all PPOs studied. Except for apple and pear PPO, the relation between decimal reduction time and inactivation temperature was log-linear in the temperature domain studied. In the case of apple and pear PPO a ‘breakpoint’ was noted at 72.5 and 75 °C, respectively. Above and below these temperatures a log-linear relation between decimal reduction time and inactivation temperature was noted. Thermal resistance of PPO seemed to be dependent on its origin. Among the polyphenoloxidases studied, grape PPO was most heat sensitive.