Asandei Alina, Schiopu Irina, Iftemi Sorana, Mereuta Loredana, Luchian Tudor
Department of Interdisciplinary Research and ‡Department of Physics, Laboratory of Molecular Biophysics and Medical Physics, Alexandru Ioan Cuza University , Boulevard Carol I, No. 11, Iasi 700506, Romania.
Langmuir. 2013 Dec 17;29(50):15634-42. doi: 10.1021/la403915t. Epub 2013 Dec 6.
Recent evidence shows that metal coordination by amyloid beta peptides (Aβ) determines structural alterations of peptides, and His-13 from Aβ is crucial for Cu(2+) binding. This study used the truncated, more soluble Aβ1-16 isoforms derived from human and rat amyloid peptides to explore their interaction with Cu(2+) by employing the membrane-immobilized α-hemolysin (α-HL) protein as a nanoscopic probe in conjunction with single-molecule electrophysiology techniques. Unexpectedly, the experimental data suggest that unlike the case of the human Aβ1-16 peptide, Cu(2+) complexation by its rat counterpart leads to an augmented association and dissociation kinetics of the peptide reversible interaction with the protein pore, as compared to the Cu(2+)-free peptide. Single-molecule electrophysiology data reveal that both human and rat Cu(2+)-complexed Aβ peptides induce a higher degree of current flow obstruction through the α-HL pore, as compared to the Cu(2+)-free peptides. It is suggested that morphology changes brought by Cu(2+) binding to such amyloidic fragments depend crucially upon the presence of the His-13 residue on the primary sequence of such peptide fragments, and the α-HL protein-based approach provides unique opportunities and challenges to probing metal-induced folding of peptides.
最近的证据表明，淀粉样β肽（Aβ）与金属的配位作用决定了肽的结构改变，且Aβ中的组氨酸-13对于铜离子（Cu(2+)）的结合至关重要。本研究使用了源自人和大鼠淀粉样肽的截短型、溶解性更强的Aβ1-16异构体，通过将膜固定化的α-溶血素（α-HL）蛋白作为纳米探针，并结合单分子电生理学技术，来探索它们与Cu(2+)的相互作用。出乎意料的是，实验数据表明，与人类Aβ1-16肽的情况不同，大鼠的Aβ1-16肽与Cu(2+)络合后，相比于无Cu(2+)的肽，其与蛋白孔的可逆相互作用的缔合和解离动力学增强。单分子电生理学数据显示，与无Cu(2+)的肽相比，人和大鼠的Cu(2+)络合Aβ肽都会导致通过α-HL孔的电流阻塞程度更高。有人提出，Cu(2+)与此类淀粉样片段结合所带来的形态变化关键取决于此类肽片段一级序列上组氨酸-13残基的存在，且基于α-HL蛋白的方法为探究金属诱导的肽折叠提供了独特的机遇和挑战。
