Three Stages of Lysozyme Thermal Stabilization by High and Medium Charge Density Anions
Three Stages of Lysozyme Thermal Stabilization by High and Medium Charge Density Anions
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DOI：
10.1021/jp412140v
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发表时间：
2014-04-24
影响因子：
3.3
通讯作者：
Falconer, Robert J.
中科院分区：
文献类型：
--
作者：
Bye, Jordan W.;Falconer, Robert J.
添加高和中等电荷密度的阴离子（磷酸盐，硫酸盐，和氯离子）的溶菌酶在纯水中展示了三个阶段的蛋白质结构的稳定。前两个阶段对溶菌酶稳定性的影响很小，可能与蛋白质表面带电和部分电荷的离子直接相互作用有关。在第二阶段和第三阶段之间有明显的过渡;在氯化钠、硫酸二钠和磷酸氢二钠的情况下，这分别是550、210和120 mM。溶菌酶的稳定性可以通过蛋白质展开时水合所需的自由能来解释。在低离子浓度下，蛋白质的水合层与本体水处于平衡。在转变之后，大量的水被耗尽，蛋白质与离子竞争水。随着蛋白质和离子在较高盐浓度下对水的竞争，使蛋白质内部水合所需的自由能上升，并且正是这使蛋白质结构稳定。
Addition of high and medium charge density anions (phosphate, sulfate, and chloride) to lysozyme in pure water demonstrates three stages for stabilization of the protein structure. The first two stages have a minor impact on lysozyme stability and are probably associated with direct interaction of the ions with charged and partial charges on the protein's surface. There is a clear transition between the second and third stages; in the case of sodium chloride, disodium sulfate and disodium hydrogen phosphate this is at 550, 210, and 120 mM, respectively. Stabilization of lysozyme can be explained by the free energy required to hydrate the protein as it unfolds. At low ion concentrations, the protein's hydration layer is at equilibrium with the bulk water. After the transition, bulk water is depleted and the protein is competing for water with the ions. With competition for water between the protein and the ions at higher salt concentrations, the free energy required to hydrate the interior of the protein rises and it is this that stabilizes the protein structure.