Bitan G, Lomakin A, Teplow D B
Center for Neurologic Diseases, Brigham and Women's Hospital, Department of Neurology (Neuroscience), Harvard Medical School, Boston, Massachusetts 02115, USA.
J Biol Chem. 2001 Sep 14;276(37):35176-84. doi: 10.1074/jbc.M102223200. Epub 2001 Jul 5.
Assembly of the amyloid beta-protein (Abeta) into neurotoxic oligomers and fibrils is a seminal event in Alzheimer's disease. Understanding the earliest phases of Abeta assembly, including prenucleation and nucleation, is essential for the development of rational therapeutic strategies. We have applied a powerful new method, photoinduced cross-linking of unmodified proteins (PICUP), to the study of Abeta oligomerization. Significant advantages of this method include an extremely short reaction time, enabling the identification and quantification of short lived metastable assemblies, and the fact that no pre facto structural modification of the native peptide is required. Using PICUP, the distribution of Abeta oligomers existing prior to assembly was defined. A rapid equilibrium was observed involving monomer, dimer, trimer, and tetramer. A similar distribution was seen in studies of an unrelated amyloidogenic peptide, whereas nonamyloidogenic peptides yielded distributions indicative of a lack of monomer preassociation. These results suggest that simple nucleation-dependent polymerization models are insufficient to describe the dynamic equilibria associated with prenucleation phases of Abeta assembly.
淀粉样β蛋白（Aβ）组装成神经毒性寡聚体和原纤维是阿尔茨海默病中的一个关键事件。了解Aβ组装的最早阶段，包括成核前阶段和核化阶段，对于制定合理的治疗策略至关重要。我们应用了一种强大的新方法，即未修饰蛋白质的光诱导交联（PICUP），来研究Aβ寡聚化。该方法的显著优点包括反应时间极短，能够识别和定量寿命短的亚稳组装体，以及无需对天然肽进行预先的结构修饰。使用PICUP，确定了组装前存在的Aβ寡聚体的分布。观察到单体、二聚体、三聚体和四聚体之间存在快速平衡。在对一种不相关的淀粉样生成肽的研究中也观察到了类似的分布，而非淀粉样生成肽产生的分布表明缺乏单体预结合。这些结果表明，简单的依赖成核的聚合模型不足以描述与Aβ组装成核前阶段相关的动态平衡。
