Universität Duisburg-Essen, Fachbereich Chemie, Universitätstrasse 5, 45117 Essen, Germany.
J Am Chem Soc. 2011 Mar 30;133(12):4348-58. doi: 10.1021/ja107675n. Epub 2011 Mar 7.
A β-sheet-binding scaffold was equipped with long-range chemical groups for tertiary contacts toward specific regions of the Alzheimer's Aβ fibril. The new constructs contain a trimeric aminopyrazole carboxylic acid, elongated with a C-terminal binding site, whose influence on the aggregation behavior of the Aβ(42) peptide was studied. MD simulations after trimer docking to the anchor point (F19/F20) suggest distinct groups of complex structures each of which featured additional specific interactions with characteristic Aβ regions. Members of each group also displayed a characteristic pattern in their antiaggregational behavior toward Aβ. Specifically, remote lipophilic moieties such as a dodecyl, cyclohexyl, or LPFFD fragment can form dispersive interactions with the nonpolar cluster of amino acids between I31 and V36. They were shown to strongly reduce Thioflavine T (ThT) fluorescence and protect cells from Aβ lesions (MTT viability assays). Surprisingly, very thick fibrils and a high β-sheet content were detected in transmission electron microscopy (TEM) and CD spectroscopic experiments. On the other hand, distant single or multiple lysines which interact with the ladder of stacked E22 residues found in Aβ fibrils completely dissolve existing β-sheets (ThT, CD) and lead to unstructured, nontoxic material (TEM, MTT). Finally, the triethyleneglycol spacer between heterocyclic β-sheet ligand and appendix was found to play an active role in destabilizing the turn of the U-shaped protofilament. Fluorescence correlation spectroscopy (FCS) and sedimentation velocity analysis (SVA) provided experimental evidence for some smaller benign aggregates of very thin, delicate structure (TEM, MTT). A detailed investigation by dynamic light scattering (DLS) and other methods proved that none of the new ligands acts as a colloid. The evolving picture for the disaggregation mechanism by these new hybrid ligands implies transformation of well-ordered fibrils into less structured aggregates with a high molecular weight. In the few cases where fibrillar components remain, these display a significantly altered morphology and have lost their acute cellular toxicity.
一个β-折叠结合支架被装备了长程化学基团，用于与阿尔茨海默氏症 Aβ 纤维的特定区域形成三级接触。新的构建体包含一个三聚体氨基吡唑羧酸，其通过 C 末端结合位点进行了延长，研究了其对 Aβ（42）肽聚集行为的影响。三聚体对接至锚定点（F19/F20）后的 MD 模拟表明，每个复杂结构都具有不同的组，每个组都具有与特征 Aβ 区域的额外特定相互作用。每个组的成员也表现出对 Aβ 的抗聚集行为的特征模式。具体来说，远程亲脂性部分，例如十二烷基、环己基或 LPFFD 片段，可以与 I31 和 V36 之间的非极性氨基酸簇形成分散相互作用。结果表明，它们可以强烈降低硫黄素 T（ThT）荧光并保护细胞免受 Aβ 损伤（MTT 活力测定）。令人惊讶的是，在透射电子显微镜（TEM）和 CD 光谱实验中检测到非常厚的纤维和高β-折叠含量。另一方面，与 Aβ 纤维中堆叠的 E22 残基的阶梯相互作用的远距离单个或多个赖氨酸完全溶解现有的β-折叠（ThT，CD），并导致无结构的、无毒的物质（TEM，MTT）。最后，发现杂环β-折叠配体和附属物之间的三乙二醇间隔物在破坏 U 形原丝的转弯方面发挥了积极作用。荧光相关光谱（FCS）和沉降速度分析（SVA）为一些非常细、精致结构的较小良性聚集体提供了实验证据（TEM，MTT）。动态光散射（DLS）和其他方法的详细研究证明，没有一种新配体起胶体作用。这些新的杂化配体的解聚机制的发展情况表明，有序纤维转化为具有高分子量的结构较差的聚集体。在纤维成分仍然存在的少数情况下，这些显示出明显改变的形态，并失去了其急性细胞毒性。
