The onset of amelogenin nanosphere aggregation studied by small-angle X-ray scattering and dynamic light scattering
The onset of amelogenin nanosphere aggregation studied by small-angle X-ray scattering and dynamic light scattering
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DOI：
10.1016/j.jsb.2005.06.007
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发表时间：
2005-09-01
影响因子：
3
通讯作者：
Fratzl, P
中科院分区：
文献类型：
--
作者：
Aichmayer, B;Margolis, HC;Fratzl, P
具有主要疏水特性的蛋白质（称为釉原蛋白）通过形成与羟基磷灰石晶体相互作用的纳米球，在高度组织化的牙釉质组织的形成中发挥着关键作用。在本研究中，我们研究了两种重组小鼠牙釉蛋白 rM179 和 rM166 的温度和 pH 依赖性自组装，后者是缺乏 13 个氨基酸亲水性 C 末端的蛋白质的工程版本。据推测，该亲水结构域在控制 rM179 的自组装行为中发挥着重要作用。通过小角度 X 射线和中子散射以及动态光散射，我们观察到 rM179 蛋白纳米球在 pH 8 时开始聚集。全长重组蛋白的这种行为可以通过纳米球的核壳模型得到最好的解释，其中亲水性和带负电的侧链防止蛋白质疏水核心的聚集 纳米球在较低温度下形成，而由多个纳米球组成的簇在高温下开始形成。相比之下，虽然 rM166 能够形成纳米球，但它表现出非常不同的聚集行为，导致在高于室温时形成更大的沉淀物。这些结果，加上最近观察到 rM179 与 rM166 不同，可以在体外调节矿物质组织，表明全长牙釉蛋白 rM179 纳米球的聚集是牙釉质基质自组装的重要步骤。 (C) 2005 Elsevier Inc. 保留所有权利。
Proteins with predominantly hydrophobic character called amelogenins play a key role in the formation of the highly organized enamel tissue by forming nanospheres that interact with hydroxyapatite crystals. In the present investigation, we have studied the temperature and pH-dependent self-assembly of two recombinant mouse amelogenins, rM179 and rM166, the latter being an engineered version of the protein that lacks a 13 amino acid hydrophilic C-terminus. It has been postulated that this hydrophilic domain plays an important role in controlling the self-assembly behavior of rM179. By small-angle X-ray and neutron scattering, as well as by dynamic light scattering, we observed the onset of an aggregation of the rM179 protein nanospheres at pH 8. This behavior of the full-length recombinant protein is best explained by a core-shell model for the nanospheres, where hydrophilic and negatively charged side chains prevent the agglomeration of hydrophobic cores of the protein nanospheres at lower temperatures, while clusters consisting of several nanospheres start to form at elevated temperatures. In contrast, while capable of forming nanospheres, rM166 shows a very different aggregation behavior resulting in the formation of larger precipitates just above room temperature. These results, together with recent observations that rM179, unlike rM166, can regulate mineral organization in vitro, suggest that the aggregation of nanospheres of the full-length amelogenin rM179 is an important step in the self-assembly of the enamel matrix. (C) 2005 Elsevier Inc. All rights reserved.