Ugarova N N, Brovko L Iu, Rozhkova G D, Berezin I V
Biokhimiia. 1977 Jul;42(7):1212-20.
Soluble preparations of horse radish peroxidase are obtained by means of its amino groups modification with glutaric aldehyde, maleic anhydride and inert proteins including albumin. The enzyme activity is found to decrease under the modification with glutaric aldehyde and to be unchanged at all other cases. Thermal stability of the enzyme preparations obtained is studied within the temperature range from 56 to 80 degrees C. Thermostability of glutaric aldehyde-modified peroxidase is approximately 2.5-fold decreased at 56 degrees C. Thermostability of other preparations exceeds the stability of native peroxidase in 25--90 times at 56 degrees C. Thermodynamic parameters of activation for the process of irreversible thermoinactivation of native and modified enzyme are calculated. A strong compensation effect between activation enthalpy and entropy values is observed, which were changed in 1.5--2 times, while the free activation energy is changed by 2--3 kcal/mol only. Possible mechanism of the change of the enzyme thermal stability under its chemical modification is discussed.
通过用戊二醛、马来酸酐和包括白蛋白在内的惰性蛋白质对辣根过氧化物酶的氨基进行修饰，可获得其可溶性制剂。发现用戊二醛修饰时酶活性降低，而在所有其他情况下酶活性保持不变。在56至80摄氏度的温度范围内研究了所得酶制剂的热稳定性。戊二醛修饰的过氧化物酶在56摄氏度时的热稳定性大约降低了2.5倍。其他制剂在56摄氏度时的热稳定性比天然过氧化物酶的稳定性高25至90倍。计算了天然酶和修饰酶不可逆热失活过程的活化热力学参数。观察到活化焓和熵值之间有很强的补偿效应，它们变化了1.5至2倍，而自由活化能仅变化了2至3千卡/摩尔。讨论了酶化学修饰后热稳定性变化的可能机制。
