The changing face of glucagon fibrillation: Structural polymorphism and conformational imprinting
The changing face of glucagon fibrillation: Structural polymorphism and conformational imprinting
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DOI：
10.1016/j.jmb.2005.09.100
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发表时间：
2006-01-20
影响因子：
5.6
通讯作者：
Otzen, DE
中科院分区：
文献类型：
--
作者：
Pedersen, JS;Dikov, D;Otzen, DE
我们已经建立了一个时间分辨荧光分析，以研究在各种不同的条件下，在高通量格式的29个残基的肽激素胰高血糖素的原纤化。在pH 2.5下形成的原纤维在原纤维化动力学、形态学、硫磺素T染色和FTIR/CD光谱方面不同，这取决于盐、胰高血糖素浓度和原纤维化温度。表观原纤维稳定性与光谱和动力学性质相关;通常，在有利于快速原纤维化的条件（环境温度、高胰高血糖素浓度或高盐浓度）下形成的原纤维似乎比在更具挑战性的条件（高温、低胰高血糖素或低盐浓度）下形成的原纤维更不耐热。用于接种的预制原纤维的性质以朊病毒样方式遗传。因此，我们得出结论，胰高血糖素形成的原纤维的结构不是全局能量最小化的结果，而是受溶剂条件和种子印迹的动力学控制。原纤维多态性，这是越来越多的蛋白质，可能反映了原纤维没有进化的限制，以保持一个单一的活性构象。我们的研究结果突出了胰高血糖素原纤化机制的复杂性，因为即使是原纤化条件的细微变化也会改变形成的原纤的类型，或导致形成几种类型的原纤的混合物。(c)2005爱思唯尔有限公司保留所有权利。
We have established a time-resolved fluorescence assay to study fibrillation of the 29 residue peptide hormone glucagon under a variety of different conditions in a high-throughput format. Fibrils formed at pH 2.5 differ in fibrillation kinetics, morphology, thioflavin T staining and FTIR/CD spectra depending on salts, glucagon concentration and fibrillation temperature. Apparent fibrillar stability correlates with spectral and kinetic properties; generally, fibrils formed under conditions favourable for rapid fibrillation (ambient temperatures, high glucagon concentration or high salt concentration) appear less thermostable than those formed under more challenging conditions (high temperatures, low glucagon or low salt concentrations). Properties of preformed fibrils used for seeding are inherited in a prion-like manner. Thus, we conclude that the structure of fibrils formed by glucagon is not the result of the global energy minimization, but rather kinetically controlled by solvent conditions and seed-imprinting. Fibrillar polymorphism, which is being reported for an increasing number of proteins, probably reflects that fibrils have not been under evolutionary constraints to retain a single active conformation. Our results highlight the complexity of the fibrillation mechanism of glucagon, since even subtle changes in fibrillation conditions can alter the type of fibrils formed, or result in formation of mixtures of several types of fibrils. (c) 2005 Elsevier Ltd. All rights reserved.