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首页> 外文期刊>The Journal of Chemical Physics >Mechanisms and rates of nucleation of amyloid fibrils
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Mechanisms and rates of nucleation of amyloid fibrils

机译：淀粉样蛋白原纤维成核的机制和速率

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The classical nucleation theory finds the rate of nucleation proportional to the monomer concentration raised to the power, which is the "critical nucleus size," n(c). The implicit assumption, that amyloids nucleate in the same way, has been recently challenged by an alternative two-step mechanism, when the soluble monomers first form a metastable aggregate (micelle) and then undergo conversion into the conformation rich in beta-strands that are able to form a stable growing nucleus for the protofilament. Here we put together the elements of extensive knowledge about aggregation and nucleation kinetics, using a specific case of A beta(1-42) amyloidogenic peptide for illustration, to find theoretical expressions for the effective rate of amyloid nucleation. We find that at low monomer concentrations in solution and also at low interaction energy between two peptide conformations in the micelle, the nucleation occurs via the classical route. At higher monomer concentrations, and a range of other interaction parameters between peptides, the two- step "aggregation-conversion" mechanism of nucleation takes over. In this regime, the effective rate of the process can be interpreted as a power of monomer concentration in a certain range of parameters; however, the exponent is determined by a complicated interplay of interaction parameters and is not related to the minimum size of the growing nucleus (which we find to be similar to 7- 8 for A beta(1-42)). (C) 2017 Author(s).
机译：经典成核理论发现的成核成正比幂，这是单体浓度的速率“临界晶核尺寸，” N（C）。隐含的假设，即淀粉状蛋白以同样的方式形核，最近已经通过替代两步机制中，当水溶性单体首先形成的亚稳集合体（胶束）攻击，然后经历转化成构象富含β-链是能够形成为原丝稳定增长的核心。在这里，我们放在一起约聚集和成核动力学的丰富知识的元素，采用β（1-42）为了说明淀粉样蛋白的肽的特定情况下，寻找淀粉样蛋白核的效率理论表达式。我们发现，在溶液的低单体浓度，并且还在胶束两个肽构象之间的低相互作用能量，经由经典途径发生成核。在较高的单体浓度，以及一系列的肽之间相互作用的其他参数，成核的两步“聚合转换”机制接管。在此方案中，处理的效率可以被解释为在一定范围内的参数的单体浓度的功率;然而，指数是由相互作用参数的复杂的相互作用来确定，并且不相关的生长核（我们发现为类似于7- 8的Aβ（1-42））的最小尺寸。 （c）2017年作者。

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