Kinetically controlled thermal response of β2-microglobulin amyloid fibrils
Kinetically controlled thermal response of β2-microglobulin amyloid fibrils
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DOI：
10.1016/j.jmb.2005.07.033
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发表时间：
2005-09-23
影响因子：
5.6
通讯作者：
Goto, Y
中科院分区：
文献类型：
--
作者：
Sasahara, K;Naiki, H;Goto, Y
使用差示扫描量热计在10至120摄氏度的温度范围内进行量热测量，以表征β(2)-微球蛋白淀粉样纤维的热响应。淀粉样原纤维溶液的热图显示出显著的热容下降，这基本上是在纤维热展开时释放的，其中负热容变化的幅度不能用目前蛋白质结构热力学的可及表面积模型来解释。在纤维展开之前，淀粉样纤维的热容-温度曲线显示出对纤维浓度和升温速率的不寻常的依赖。特别是，发现诱导热响应所需的热与升温速率线性相关，表明其热响应受动力学控制，排除了平衡热力学的解释。此外，淀粉样β多肽的淀粉样纤维在纤维展开之前也表现出一个依赖于升温速率的放热过程，这表明动力学控制的热响应可能是淀粉样纤维的普遍现象。我们认为，热容随升温速率的负变化与淀粉样蛋白纤维与特征水合模式的关联有关。(C)2005爱思唯尔有限公司。保留所有权利。
Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta(2)-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern. (c) 2005 Elsevier Ltd. All rights reserved.