Secondary structure and folding stability of proteins adsorbed on silica particles - Pressure versus temperature denaturation.
Secondary structure and folding stability of proteins adsorbed on silica particles - Pressure versus temperature denaturation.
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二氧化硅颗粒上吸附的蛋白质的二级结构和折叠稳定性 - 压力与温度变性
DOI：
10.1016/j.colsurfb.2015.03.043
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
C. Czeslik
中科院分区：
文献类型：
--
作者：
S. Cinar;C. Czeslik
我们对吸附在二氧化硅颗粒上的蛋白质的压力和温度依赖的展开行为进行了系统的研究。以鸡蛋清溶菌酶和牛核糖核酸酶A(RNase)为模型蛋白，在温度10~90℃、压力1~16000 kbar的条件下，用傅立叶变换红外光谱(FTIR)分析了它们的二级结构。显然，当这两种蛋白质吸附在二氧化硅颗粒上时，它们的二级结构没有明显的变化。值得注意的是，蛋白质在吸附和自由状态下的二级结构元素在展开过程中的变化非常相似。在高压和高温条件下，溶菌酶和核糖核酸酶都可以观察到这种相似性。然而，溶菌酶和核糖核酸酶在吸附后的展开压力和温度显著降低，表明蛋白质在二氧化硅颗粒上的折叠稳定性较低。此外，二级结构发生变化的温度范围由于吸附而变宽，这与展开的热焓变化较小有关。对于这两种蛋白质，无论是游离的还是吸附的，压力诱导的去折叠总是比温度诱导的去折叠导致的二级结构变化不那么明显。在溶菌酶的情况下，高压也有利于不同的展开构象而不是高温。总体而言，本研究的结果表明，蛋白质在二氧化硅颗粒上的吸附降低了蛋白质在高压和高温下的折叠稳定性，而去折叠途径主要保留在吸附状态。
We present a systematic study of the pressure and temperature dependent unfolding behavior of proteins that are adsorbed on silica particles. Hen egg white lysozyme and bovine ribonuclease A (RNase) were used as model proteins, and their secondary structures were resolved by Fourier transform infrared (FTIR) spectroscopy in the temperature range of 10–90 °C and the pressure range of 1–16,000 bar. Apparently, the secondary structures of both proteins do not change significantly when they are adsorbing on the silica particles. Remarkably, the changes of the secondary structure elements upon protein unfolding are very similar in the adsorbed and the free states. This similarity could be observed for both lysozyme and RNase using both high pressures and high temperatures as denaturing conditions. However, the pressures and temperatures of unfolding of lysozyme and RNase are drastically lowered upon adsorption indicating lower folding stabilities of the proteins on the silica particles. Moreover, the temperature ranges, where changes in secondary structure occur, are broadened due to adsorption, which is related to smaller enthalpy changes of unfolding. For both proteins, free or adsorbed, pressure-induced unfolding always leads to less pronounced changes in secondary structure than temperature-induced unfolding. In the case of lysozyme, high pressure also favors a different unfolded conformation than high temperature. Overall, the results of this study reveal that adsorption of proteins on silica particles decreases the folding stability against high pressures and temperatures, whereas the unfolding pathways are mainly preserved in the adsorbed state.