The effects of NaCl concentration and pH on the stability of hyperthermophilic protein Ssh10b.
The effects of NaCl concentration and pH on the stability of hyperthermophilic protein Ssh10b.
复制标题
NaCl浓度和pH对超嗜热蛋白Ssh10b稳定性的影响。
DOI：
10.1186/1471-2091-8-28
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发表时间：
2007-12-21
期刊：
影响因子：
--
通讯作者：
Pan XM
中科院分区：
文献类型：
--
作者：
Mao YJ;Sheng XR;Pan XM
超嗜热菌是一类最适生长温度在80°C至100°C之间的微生物。虽然蛋白质热稳定性的分子基础已经成为许多理论和实验工作的焦点，但导致超嗜热蛋白质更高变性温度的性质仍然存在争议。在众多影响超嗜热蛋白热稳定性的因素中，静电相互作用被认为是一个普遍重要的因素。在这项研究中，我们报告的pH值和盐浓度的影响尿素诱导的蛋白质Ssh 10 b从超嗜热菌在低离子强度缓冲液中的变性。在不存在NaCl的情况下，蛋白质的去折叠ΔG从pH 3时的约33 kJ/mol增加到pH 10时的约78 kJ/mol。在所有pH值下，ΔG随着NaCl浓度的增加而增加，表明盐显著稳定蛋白质。这些研究结果表明，在蛋白质Ssh 10 b从hyperthermophiles中的带电残基和离子对的数量增加并不有助于稳定的折叠蛋白质，但可能发挥作用，在确定的变性状态合奏，也在增加变性温度。
Hyperthermophiles constitute a group of microorganisms with an optimum growth temperature of between 80°C and 100°C. Although the molecular underpinnings of protein thermostabilization have been the focus of many theoretical and experimental efforts, the properties leading to the higher denaturation temperature of hyperthermophilic proteins are still controversial. Among the large number of factors identified as responsible for the thermostability of hyperthermophilic proteins, the electrostatic interactions are thought to be a universally important factor. In this study, we report the effects of pH and salt concentration on the urea-induced denaturation of the protein Ssh10b from a hyperthermophile in low ionic strength buffer. In the absence of NaCl, the unfolding ΔG of the protein increased from about 33 kJ/mol at pH 3 to about 78 kJ/mol at pH 10. At all values of pH, the ΔG increased with increasing NaCl concentration, indicating that salt stabilizes the protein significantly. These findings suggests that the increased number of charged residues and ion pairs in the protein Ssh10b from hyperthermophiles does not contribute to the stabilization of the folded protein, but may play a role in determining the denatured state ensemble and also in increasing the denaturation temperature.