Direct measurement of the thermodynamic parameters of amyloid formation by isothermal titration calorimetry
Direct measurement of the thermodynamic parameters of amyloid formation by isothermal titration calorimetry
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DOI：
10.1074/jbc.m409677200
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发表时间：
2004-12-31
影响因子：
4.8
通讯作者：
Goto, Y
中科院分区：
文献类型：
--
作者：
Kardos, J;Yamamoto, K;Goto, Y
淀粉样原纤维沉积与 20 多种退行性疾病有关，包括阿尔茨海默病、帕金森病和朊病毒病。尽管过去几年的研究揭示了淀粉样蛋白形式的形态和结构特征，但有关淀粉样蛋白形成的热力学的知识仍然有限。在这里，我们首次报告使用等温滴定量热法对淀粉样蛋白形成的直接热力学研究。 β(2)-微球蛋白是一种与透析相关的淀粉样变性有关的蛋白质，用于在热量计细胞的种子控制反应中延伸淀粉样原纤维。我们研究了反应的焓和热容变化，其中单体、酸变性分子在刚性淀粉样原纤维中采用有序的、交叉β-折叠结构。尽管形态上存在显着差异，β(2)-微球蛋白在淀粉样蛋白形成时表现出与折叠成天然球状状态相似的热容变化，而反应的焓变被证明明显较低。与天然状态相比，结果概述了淀粉样蛋白原纤维的重要结构特征：即使淀粉样蛋白原纤维的超分子结构，表面埋藏程度相似，内部堆积水平较低，以及可能存在不利的侧链贡献。
Amyloid fibril deposition is associated with over 20 degenerative diseases, including Alzheimer's, Parkinson's, and prion diseases. Although research over the last few years has revealed the morphology and structural features of the amyloid form, knowledge about the thermodynamics of amyloid formation is limited. Here, we report for the first time a direct thermodynamic study of amyloid formation using isothermal titration calorimetry. beta(2)-Microglobulin, a protein responsible for dialysis-related amyloidosis, was used for extending amyloid fibrils in a seed-controlled reaction in the cell of the calorimeter. We investigated the enthalpy and heat capacity changes of the reaction, where the monomeric, acid-denatured molecules adopt an ordered, cross-beta-sheet structure in the rigid amyloid fibrils. Despite the dramatic difference in morphology, beta(2)-microglobulin exhibited a similar heat capacity change upon amyloid formation to that of the folding to the native globular state, whereas the enthalpy change of the reaction proved to be markedly lower. In comparison with the native state, the results outline the important structural features of the amyloid fibrils: a similar extent of surface burial even with the supramolecular architecture of amyloid fibrils, a lower level of internal packing, and the possible presence of unfavorable side chain contributions.