Effects of surface charge on denaturation of bovine carbonic anhydrase
Effects of surface charge on denaturation of bovine carbonic anhydrase
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DOI：
10.1002/cbic.200600191
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发表时间：
2006-08-01
期刊：
影响因子：
3.2
通讯作者：
Whitesides, George M.
中科院分区：
文献类型：
--
作者：
Gitlin, Irina;Gudiksen, Katherine L.;Whitesides, George M.
本研究比较了两种蛋白质-牛碳酸酐酶II （BCA）及其衍生物与油赖氨酸基乙酰化(BCA- ac -18)-通过尿素、氯化胍（GuHCl）、热和十二烷基硫酸钠（SDS）的变性。结果表明，赖氨酸乙酰化使蛋白质的净负电荷增加，降低了蛋白质对尿素、GuHCl和热的稳定性，但增加了其对SDS变性的动力学稳定性（其热力学稳定性无法测量）。增加缓冲液的离子强度可以提高BCA- ac -18对尿素和热的稳定性，但仍比未乙酰化的BCA对这些变性剂的稳定性差。在尿素中，静电相互作用的巨大变化不仅改变了变性的自由能，而且在展开途径中引入了稳定的中间体。这项工作表明，蛋白质表面电荷的修饰对蛋白质的稳定性有很大的影响——正的或负的，取决于变性剂——尽管这些电荷暴露在高介电溶剂和缓冲离子中。
This work compares the denaturation of two proteins-bovine carbonic anhydrase II (BCA) and its derivative with oil lysine groups acetylated (BCA-Ac-18)-by urea, guanidinium chloride (GuHCl), heat, and sodium dodecyl sulfate (SDS). It demonstrates that increasing the net negative charge of the protein by acetylation of lysines reduces its stability to urea, GuHCl, and heat, but increases its kinetic stability (its thermodynamic stability cannot be measured) towards denaturation by SDS. Increasing the ionic strength of the buffer improves the stability of BCA-Ac-18 to urea and heat, but still leaves it less stable than unacetylated BCA to those denaturants. In urea, the large change in electrostatic interactions not only modifies the free energy of denaturation, but also introduces a stable intermediate into the unfolding pathway. This work shows that modifications of charges on the surfaces of proteins con hove a large effect-positive or negative, depending on the denaturant-on the stability of the proteins despite the exposure of these charges to high dielectric solvent and buffer ions.