Nayak Arpan, Sorci Mirco, Krueger Susan, Belfort Georges
Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
Proteins. 2009 Feb 15;74(3):556-65. doi: 10.1002/prot.22169.
To help identify the etiological agents for amyloid-related diseases, attention is focused here on the fibrillar precursors, also called oligomers and protofibrils, and on modeling the reaction kinetics of the formation of the amyloid nucleus. Insulin is a favored model for amyloid formation, not only because amyloidosis can be a problem in diabetes, but also because aggregation and fibrillation causes problems during production, storage, and delivery. Small angle neutron scattering (SANS) is used to measure the temporal formation of insulin oligomers in H(2)O- and D(2)O-based solvents and obtain consistent evidence of the composition of the insulin nucleus that comprised three dimers or six monomers similar to that recently proposed in the literature. A simple molecular structural model that describes the growth of oligomers under a wide range of environmental conditions is proposed. The model first involves lengthening or end-on-end association of dimers to form three-dimer nuclei, and then exhibits broadening or side-on-side association of nuclei. Using different additives to demonstrate their influence on the kinetics of oligomer formation, we showed that, although the time required to form the nucleus was dependent on a specific system, they all followed a universal pathway for nucleus and precursor formation. The methods and analyses presented here provide the first experimental molecular size description of the details of amyloid nucleus formation and subsequent propagation to fibril precursors independent of kinetics.
为了帮助确定淀粉样蛋白相关疾病的病原体，本文重点关注纤维状前体，也称为寡聚体和原纤维，并对淀粉样蛋白核形成的反应动力学进行建模。胰岛素是淀粉样蛋白形成的一个理想模型，这不仅是因为淀粉样变性在糖尿病中可能是一个问题，还因为聚集和纤维化在生产、储存和运输过程中会引发问题。小角中子散射（SANS）用于测量基于H₂O和D₂O的溶剂中胰岛素寡聚体随时间的形成，并获得胰岛素核组成的一致证据，该核由三个二聚体或六个单体组成，与最近文献中提出的相似。提出了一个简单的分子结构模型，该模型描述了在广泛的环境条件下寡聚体的生长。该模型首先涉及二聚体的延长或端对端结合以形成三聚体核，然后表现为核的加宽或并排结合。通过使用不同的添加剂来证明它们对寡聚体形成动力学的影响，我们表明，尽管形成核所需的时间取决于特定系统，但它们都遵循核和前体形成的通用途径。本文介绍的方法和分析首次提供了对淀粉样蛋白核形成细节以及随后向纤维状前体传播的实验性分子大小描述，且与动力学无关。
