Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States.
Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, California 92697, United States.
ACS Chem Neurosci. 2022 Mar 16;13(6):714-720. doi: 10.1021/acschemneuro.1c00833. Epub 2022 Feb 22.
This work probes the role of charge in the oligomeric assembly, toxicity, and membrane destabilization of a series of peptides derived from Aβ and the E22Q and E22K familial mutants. In the mutant Aβ peptides, an acidic residue (E) is replaced with either a neutral or basic residue (Q or K), thus altering the net charge of the peptide. Acetylation at peripheral positions permits modulation of charge of the peptides and allows investigation of the role of charge in their oligomeric assembly, cytotoxicity, and membrane disruption. Peptides with the same net charge generally behave similarly even if the amino acid residue at position 22 differs. As the net charge of the peptide decreases, so does the extent of assembly, cytotoxicity, and membrane destabilization, which were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, lactate dehydrogenase (LDH)-release assays with SH-SY5Y cells, and dye leakage assays using liposomes. These findings suggest that the charge of the amino acid side chain, rather than its size or hydrophobicity, accounts for the differences in the oligomeric assembly and toxicity of the E22 familial mutants of Aβ.
这项工作探究了一系列源自 Aβ 的肽以及 E22Q 和 E22K 家族突变体的电荷在寡聚体组装、毒性和膜破坏中的作用。在突变 Aβ 肽中，带负电荷的残基（E）被中性或碱性残基（Q 或 K）取代，从而改变了肽的净电荷。在侧链位置乙酰化可以调节肽的电荷，并允许研究电荷在它们的寡聚体组装、细胞毒性和膜破坏中的作用。具有相同净电荷的肽通常表现相似，即使在 22 位的氨基酸残基不同的情况下也是如此。随着肽的净电荷降低，寡聚体组装、细胞毒性和膜破坏的程度也降低，这可以通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、SH-SY5Y 细胞的乳酸脱氢酶（LDH）释放试验和使用脂质体的染料渗漏试验来确定。这些发现表明，氨基酸侧链的电荷而不是其大小或疏水性决定了 E22 家族突变体 Aβ 的寡聚体组装和毒性的差异。
