Tuning Chelation by the Surfactant-Like Peptide A6H Using Predetermined pH Values

详细信息    查看全文

• 作者：V. Castelletto ; I. W. Hamley ; M. D. Segarra-Maset ; C. Berdugo Gumbau ; J. F. Miravet ; B. Escuder ; J. Seitsonen ; J. Ruokolainen
• 刊名：Biomacromolecules
• 出版年：2014
• 出版时间：February 10, 2014
• 年：2014
• 卷：15
• 期：2
• 页码：591-598
• 全文大小：517K
• ISSN：1526-4602

文摘

We examine the self-assembly of a peptide A₆H comprising a hexa-alanine sequence A₆ with a histidine (H) 鈥渉ead group鈥? which chelates Zn²⁺ cations. We study the self-assembly of A₆H and binding of Zn²⁺ ions in ZnCl₂ solutions, under acidic and neutral conditions. A₆H self-assembles into nanotapes held together by a 尾-sheet structure in acidic aqueous solutions. By dissolving A₆H in acidic ZnCl₂ solutions, the carbonyl oxygen atoms in A₆H chelate the Zn²⁺ ions and allow for 尾-sheet formation at lower concentrations, consequently reducing the onset concentration for nanotape formation. A₆H mixed with water or ZnCl₂ solutions under neutral conditions produces short sheets or pseudocrystalline tapes, respectively. The imidazole ring of A₆H chelates Zn²⁺ ions in neutral solutions. The internal structure of nanosheets and pseudocrystalline sheets in neutral solutions is similar to the internal structure of A₆H nanotapes in acidic solutions. Our results show that it is possible to induce dramatic changes in the self-assembly and chelation sites of A₆H by changing the pH of the solution. However, it is likely that the amphiphilic nature of A₆H determines the internal structure of the self-assembled aggregates independent from changes in chelation.