Characterization of copper interactions with Alzheimer amyloid β peptides:: Identification of an attomolar-affinity copper binding site on amyloid β1-42
Characterization of copper interactions with Alzheimer amyloid β peptides:: Identification of an attomolar-affinity copper binding site on amyloid β1-42
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DOI：
10.1046/j.1471-4159.2000.0751219.x
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发表时间：
2000-09-01
影响因子：
4.7
通讯作者：
Bush, AI
中科院分区：
文献类型：
--
作者：
Atwood, CS;Scarpa, RC;Bush, AI
铜和锌已被证明在阿尔茨海默病患者的大脑中积累。我们以前曾报道，铜2+和锌2+结合淀粉样蛋白β（A β），解释其富集斑块病理。在这里，我们详细介绍了化学计量和结合亲和力的多个合作铜+结合位点的合成A β 1-40和A β 1-42。我们开发了一种配体置换技术（竞争性金属捕获分析），该技术使用金属螯合剂络合物来评估金属离子与A β（一种众所周知的自聚集肽）的结合。该分析表明，A β 1-42上存在介导肽沉淀的非常高亲和力的Cu 2+结合位点（log K-app = 17.2），并且该肽在水溶液中自聚集的趋势是由于存在痕量Cu 2+污染（通常类似于0.1 μ M）。相比之下，A β 1-40在该位点对Cu 2+具有低得多的亲和力（估计log K-app = 10.3），这解释了为什么该肽较少自聚集。与A β 1-40相比，A β 1- 42的更大的Cu 2+结合亲和力与显著降低的负协同性相关。通过证明A β肽（10 μ M）仅在高亲和力Cu 2+选择性螯合剂存在下保持可溶5天，证实了微量金属污染在诱导A β沉淀中的作用。
Cu and Zn have been shown to accumulate in the brains of Alzheimer's disease patients. We have previously reported that Cu2+ and Zn2+ bind amyloid beta (A beta), explaining their enrichment in plaque pathology. Here we detail the stoichiometries and binding affinities of multiple cooperative Cu2+-binding sites on synthetic A beta 1-40 and A beta 1-42. We have developed a ligand displacement technique (competitive metal capture analysis) that uses metal-chelator complexes to evaluate metal ion binding to A beta, a notoriously self-aggregating peptide. This analysis indicated that there is a very-high-affinity Cu2+-binding site on A beta 1-42 (log K-app = 17.2) that mediates peptide precipitation and that the tendency of this peptide to self-aggregate in aqueous solutions is due to the presence of trace Cu2+ contamination (customarily similar to 0.1 mu M). In contrast, A beta 1-40 has much lower affinity for Cu2+ at this site (estimated log K-app = 10.3), explaining why this peptide is less self-aggregating. The greater Cu2+-binding affinity of A beta 1-42 compared with A beta 1-40 is associated with significantly diminished negative cooperativity, The role of trace metal contamination in inducing A beta precipitation was confirmed by the demonstration that A beta peptide (10 mu M) remained soluble for 5 days only in the presence of high-affinity Cu2+-selective chelators.