Effect of temperature on the adsorption of lysozyme at the silica/water interface studied by optical and neutron reflectometry
Effect of temperature on the adsorption of lysozyme at the silica/water interface studied by optical and neutron reflectometry
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DOI：
10.1021/la025605i
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发表时间：
2002-08-20
期刊：
影响因子：
3.9
通讯作者：
Czeslik, C
中科院分区：
文献类型：
--
作者：
Jackler, G;Steitz, R;Czeslik, C
研究了温度对鸡蛋白色溶菌酶在硅胶/水界面上吸附的影响。通过使用光学反射计，已确定在一个大的温度范围内与蛋白质溶液浓度范围从0.03至0.09毫克毫升（-1）的吸附质量每表面积。已经发现，吸附的蛋白质的量通过温度的增加而强烈增加，这表明吸热并且因此是熵驱动的吸附过程。这可以通过吸附诱导的蛋白质构象的改变来解释。在高温下，溶解的溶菌酶主要是未折叠的，疏水脱水效应也将发挥作用。实验结果支持了蛋白质在界面上的吸附比稳定蛋白质更强的观点。吸附的正焓表明，吸附物中蛋白质分子之间存在明显的静电排斥作用。已确定在23，63，和80 degreesC使用中子反射法的溶菌酶吸附物的浓度分布。在每个温度下，三个反射率曲线已被测量应用对比度变化的方法。的反射率已拟合全球的基础上的四层模型，Si/SiO2/吸附质/解决方案。所获得的浓度曲线清楚地表明，在23-63 ℃的范围内，温度诱导的二氧化硅/水界面处的溶菌酶吸附程度的增加部分是由吸附物中的溶菌酶的更致密的堆积引起的。而中子反射率数据是一致的单层吸附在23和63 degreesC，至少有两层蛋白质分子吸附在80 degreesC。
The effect of temperature on the adsorption of hen egg white lysozyme at the silica/water interface has been studied. By use of optical reflectometry, the adsorbed mass per surface area has been determined over a large temperature range with protein solution concentrations ranging from 0.03 to 0.09 mg mL(-1). It has been found that the amount of adsorbed protein is strongly increased by an increase in temperature, which indicates an endothermic and thus an entropy-driven adsorption process. This can be explained by an adsorption-induced modification of the protein conformation. At high temperatures, where dissolved lysozyme is mainly unfolded, hydrophobic dehydration effects will play a role as well. The results support the concept that thermodynamically unstable proteins adsorb more strongly at interfaces than stable proteins The positive enthalpy of adsorption suggests that significant repulsive electrostatic interactions between the protein molecules of the adsorbate are present. Concentration profiles of lysozyme adsorbates have been determined at 23, 63, and 80 degreesC using neutron reflectometry. At each temperature, three reflectivity curves have been measured applying the contrast variation method. The reflectivities have been fitted globally on the basis of a four-layer model, Si/SiO2/adsorbate/solution. The obtained concentration profiles clearly show that in the range of 23-63 degreesC the temperature-induced increase of the degree of lysozyme adsorption at the silica/water interface is caused in part by a denser packing of the lysozyme,in the adsorbate. Whereas the neutron reflectivity data are consistent with a monolayer adsorption at 23 and 63 degreesC, at least two layers of protein molecules are adsorbed at 80 degreesC.