嗜热酶耐热机制的研究进展

Advances in Research of Mechanisms of Thermostability of Thermozymes

从极端环境中筛选的嗜热菌、超嗜热菌(包括古菌)是嗜热酶的主要来源,但由于嗜热菌的培养条件严格、产酶量低等缺点,使基因工程及蛋白质工程成为生产嗜热酶的又一手段。目前,比较嗜热酶与同源常温酶的氨基酸序列的同源性是研究嗜热酶耐热性的主要方法。不同的酶其耐热机制不同,在一级结构中,嗜热酶具有与同源常温酶不同的氨基酸组成。α-螺旋的稳定性使嗜热酶在二级结构上更稳定。在高级结构中,“额外”的离子键、疏水作用、氢键、寡聚体的形成等对嗜热酶的耐热性起主要作用。一些环境因子也影响嗜热酶的耐热性。

Thermophiles and hyperthermophiles screened from extreme environments are the main source of thermozymes. Because of thermophiles' harsh cultural condition and low enzyme quantities, gene engineering and protein engineering are also methods of obtaining thermozymes. At the present time, It is a major method of research on the thermostability of thermozymes to compare the homology of amino acid sequence between thermozymes and mesophilic enzymes. The different enzymes have different mechanisms of thermostability. The amino acid composition between thermozymes and their mesophilic counterparts is different in the primary structure. α-helix stabilization increases thermozymes' stability in secondary structure. In advanced structure, internal factors of thermophilic enzymes are of importance, such as 'additional' ionic networks, hydrophobic interactions, hydrogen bonds, cooperative association, etc. Some environmental factors have effect on thermostability of thermozymes.