Halophilic enzymes: proteins with a grain of salt
Halophilic enzymes: proteins with a grain of salt
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DOI：
10.1016/s0301-4622(00)00126-5
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发表时间：
2000-08-30
影响因子：
3.8
通讯作者：
Gloss, LM
中科院分区：
文献类型：
--
作者：
Mevarech, M;Frolow, F;Gloss, LM
尽管嗜盐酶与非嗜盐酶具有相同的酶功能，但它们表现出显著不同的性质，其中包括对1-4M范围内的高盐浓度的活性和稳定性的要求，以及对碱性氨基酸残基的高过量酸性。本文综述了极端嗜盐古细菌Haloarcula marismortui的两种蛋白质的功能和结构特性：苹果酸脱氢酶(HMDH)和2Fe-2S蛋白铁氧还蛋白。有人认为，嗜盐蛋白质的高表面负电荷使其更易溶解，并使其在高盐浓度下更具弹性，在这种条件下，非嗜盐蛋白质容易聚集并变得僵硬。这种高表面电荷主要被紧密结合的水偶极子所中和。另一方面，由于盐与折叠多肽表面特定位置的低亲和力结合，从而稳定了蛋白质的活性构象，因此需要较高的盐浓度来稳定嗜盐酶的稳定性。(C)2000 Elsevier Science B.V.保留所有权利。
Halophilic enzymes, while performing identical enzymatic functions as their non-halophilic counterparts, have been shown to exhibit substantially different properties, among them the requirement for high salt concentrations, in the 1-4 M range, for activity and stability, and a high excess of acidic over basic amino residues. The following communication reviews the functional and structural properties of two proteins isolated from the extremely halophilic archaeon Haloarcula marismortui: the enzyme malate-dehydrogenase (hMDH) and the 2Fe-2S protein ferredoxin. It is argued that the high negative surface charge of halophilic proteins makes them more soluble and renders them more flexible at high salt concentrations, conditions under which non-halophilic proteins tend to aggregate and become rigid. This high surface charge is neutralized mainly by tightly bound water dipoles. The requirement of high salt concentration for the stabilization of halophilic enzymes, on the other hand, is due to a low affinity binding of the salt to specific sites on the surface of the folded polypeptide, thus stabilizing the active conformation of the protein. (C) 2000 Elsevier Science B.V. All rights reserved.