Heat-induced conversion of β2-Microglobulin and hen egg-white lysozyme into amyloid fibrils
Heat-induced conversion of β2-Microglobulin and hen egg-white lysozyme into amyloid fibrils
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DOI：
10.1016/j.jmb.2007.06.088
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发表时间：
2007-09-28
影响因子：
5.6
通讯作者：
Goto, Yuji
中科院分区：
文献类型：
--
作者：
Sasahara, Kenji;Yagi, Hisashi;Goto, Yuji
通过差示扫描量热法(DSC)可以直接获得完全可逆折叠/去折叠体系中表征蛋白质稳定性的热力学参数。然而，可逆的DSC图谱可以通过引起聚集的不可逆步骤来改变。在这里，为了深入了解导致各种淀粉样变性的淀粉样纤维、有序和纤维状聚集体，我们研究了搅拌和加热组合对人β(2)-微球蛋白和蛋清溶菌酶的影响。在DSC仪器的池中加热天然状态的蛋白质溶液在氯化钠存在下温和搅拌形成的聚集体。对于β(2)-微球蛋白，随着中性pH下氯化钠浓度的增加，热谱开始显示放热转变，伴随着热容的大幅下降，随后是动力学控制的热响应。类似地，在高浓度的氯化钠中聚集的溶菌酶在较宽的pH范围内显示出类似的明显的DSC热谱转变。电子显微镜显示构象变化为淀粉样纤维。总而言之，结合使用搅拌和加热是从两种蛋白质(β(2)-微球蛋白和蛋清溶菌酶)中产生淀粉样原纤维的有效方法，并评估热对原纤化的影响，其中热容量是表征转变的关键。(C)2007爱思唯尔有限公司。保留所有权利。
Thermodynamic parameters characterizing protein stability can be obtained for a fully reversible folding/unfolding system directly by differential scanning calorimetry (DSC). However, the reversible DSC profile can be altered by an irreversible step causing aggregation. Here, to obtain insight into amyloid fibrils, ordered and fibrillar aggregates responsible for various amyloidoses, we studied the effects on human beta(2)-microglobulin and hen egg-white lysozyme of a combination of agitation and heating. Aggregates formed by mildly agitating protein solutions in the native state in the presence of NaCl were heated in the cell of the DSC instrument. For beta(2)-microglobulin, with an increase in the concentration of NaCl at neutral pH, the thermogram began to show an exothermic transition accompanied by a large decrease in heat capacity, followed by a kinetically controlled thermal response. Similarly, the aggregated lysozyme at a high concentration of NaCl revealed a similar distinct transition in the DSC thermogram over a wide pH range. Electron microscopy demonstrated the conformational change into amyloid fibrils. Taken together, the combined use of agitation and heating is a powerful way to generate amyloid fibrils from two proteins, beta(2)-microglobulin and hen egg-white lysozyme, and to evaluate the effects of heat on fibrillation, in which the heat capacity is crucial to characterizing the transition. (c) 2007 Elsevier Ltd. All rights reserved.