Alternate aggregation pathways of the Alzheimer β-amyloid peptide:: Aβ association kinetics at endosomal pH
Alternate aggregation pathways of the Alzheimer β-amyloid peptide:: Aβ association kinetics at endosomal pH
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DOI：
10.1016/s0022-2836(02)01279-2
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发表时间：
2003-01-24
影响因子：
5.6
通讯作者：
Chakrabartty, A
中科院分区：
文献类型：
--
作者：
Gorman, PM;Yip, CM;Chakrabartty, A
神经元周围 β-淀粉样肽 (Abeta) 原纤维的沉积是阿尔茨海默病的一个不变特征，并且越来越多的证据表明原纤维沉积和/或前原纤维中间体在观察到的神经变性中发挥着核心作用。 Abeta 产生的位点之一是内体，我们研究了在内体 pH 值下生理相关时间范围内 Abeta 关联的动力学。我们已经确定了三个不同的 Abeta 关联阶段，其发生率与内体转运时间相当。在 15 秒内观察到大于 200 nm 的爆发相聚集体的快速形成。通过荧光共振能量转移检测到两个较慢的缔合相，并将其称为相 1 和相 2 聚集反应。在 20 muM Abeta、pH 6 下，第 1 相和第 2 相聚集相的半衰期分别为 3.15 分钟和 17.66 分钟。原子力显微镜和动态光散射研究表明，爆裂相聚集体较大且无定形，而第一相和第二相聚集体是球形，流体动力学半径约为 30 nm。在大的爆发相聚集体与相 1 和相 2 球形颗粒之间存在明显的平衡，可能是通过可溶性 Abeta 中间体介导的。大的爆发相聚集体很快形成，然而，随着平衡向球形聚集体移动，它们消失。根据圆二色光谱测定，这些聚集的物质不包含 α 螺旋或 β 结构。然而，两周后观察到β-结构，这归因于样品的不溶部分。两个月后，成熟的淀粉样原纤维出现，球形聚集体显着减少。 (C) 2003 Elsevier Science Ltd. 保留所有权利。
The deposition of beta-amyloid peptide (Abeta) fibrils around neurons is an invariable feature of Alzheimer's disease and there is increasing evidence that fibrillar deposits and/or Prefibrillar intermediates play a central role in the observed neurodegeneration. One site of Abeta generation is the endosomes, and we have investigated the kinetics of Abeta association at endosomal pH over physiologically relevant time frames. We have identified three distinct Abeta association phases that occur at rates comparable to endosomal transit times. Rapid formation of burst phase aggregates, larger than 200 nm, was observed within 15 seconds. Two slower association phases were detected by fluorescence resonance energy transfer and termed phase 1 and phase 2 aggregation reactions. At 20 muM Abeta, pH 6, the half lives of the phase 1 and phase 2 aggregation phases were 3.15 minutes and 17.66 minutes, respectively. Atomic force microscopy and dynamic light scattering studies indicate that the burst phase aggregate is large and amorphous, while phase 1 and 2 aggregates are spherical with hydrodynamic radii around 30 nm. There is an apparent equilibrium, potentially mediated through a soluble Abeta intermediate, between the large burst phase aggregates and phase 1 and 2 spherical particles. The large burst phase aggregates form quickly, however, they disappear as the equilibrium shifts toward the spherical aggregates. These aggregated species do not contain alpha-helical or beta-structure as determined by circular dichroism spectroscopy. However, after two weeks beta-structure is observed and is attributable to the insoluble portion of the sample. After two months, mature amyloid fibrils appear and the spherical aggregates are significantly diminished. (C) 2003 Elsevier Science Ltd. All rights reserved.