Title
Conformation and Self-Assembly Changes of Isomeric Peptide Amphiphiles Influenced by Switching Tyrosine in the Sequences
Author
Fangyi Zhao, Hui Guo, Zhidong Zhang, John Ye, Longlong Liu, Chun-Xia Zhao, Zhengzhong Shao
Year
2017
Journal
Journal of Materials Chemistry B
Abstract
Self-assemblies of peptide amphiphiles feature their unique structures, high biocompatibility, potential for various applications and have attracted increasing interest in supramolecular chemistry, protein science and polymer science. In this paper, isomeric peptide amphiphiles derived from lauric acid and silk fibroin-based peptides with different amino acid sequences (GAGAGAGY, GAGAGYGA, GAGYGAGA and GYGAGAGA) are investigated systematically to figure out the predominately endogenous and exogenous factors on their assembling in aqueous solution. With the position of tyrosine (Y) in the peptide segment gradually moving towards the alkane tails, the assembled peptide amphiphiles substantially change their secondary structures from β-sheet to disorder dominant one at neutral pH ambient, because the increasing of steric hindrances induced by the position change of Y disturbs the hydrogen bonds relevant to the formation of β-sheet of (GA)n. Strong alkaline condition is able to accelerate such conformational change, due to the synergy of destruction of hydrogen bonds, steric-hindrance effect and electrostatic repulsion. As the consequence, the assembled peptide amphiphiles alter their nanostructures in aqueous solution from well-defined nanofibers to nanospheres with varied sizes. Therefore, it is summarized that the location of Y rather than the other effects such as pH value etc. acts as an essential role in the assembling of our isomeric peptide amphiphiles, which shines a light on the design of various isomeric peptides/peptide amphiphiles for their aggregation as well as the potential functionality.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Chemical stability, Biochemistry, Materials