Self-Assembling Behavior of pH-Responsive Peptide A6K without End-Capping

Abstract

A short self-assembly peptide A6K (H2N−AAAAAAK−OH) with unmodified N− and C−terminus was designed, and the charge distribution model of this short peptide at different pH was established by computer simulation. The pH of the solution was adjusted according to the model and the corresponding self-assembled structure was observed using a transmission electron microscope (TEM). As the pH changes, the peptide will assemble into blocks or nanoribbons, which indicates that the A6K peptide is a pH-responsive peptide. Circular dichroism (CD) and molecular dynamics (MD) simulation showed that the block structure was formed by random coils, while the increase in β-turn content contributes to the formation of intact nanoribbons. A reasonable explanation of the self-assembling structure was made according to the electrostatic distribution model and the effect of electrostatic interaction on self-assembly was investigated. This study laid the foundation for further design of nanomaterials based on pH-responsive peptides.

Self‐assembling Peptides with Internal Ionizable Unnatural Amino Acids: A General Approach to pH‐responsive Peptide Materials

“…[26,27] Amino acids with an ionizable side chain, such as lysine or glutamic acid have been commonly selected and placed in a hydrophilic domain of a synthetic peptide to control the pH-dependent self-assembly process. [6,9,[28][29][30][31][32][33][34][35][36][37] In particular, recently it was discovered that by judicious selection of amino acid building blocks, pH-responsive peptides can form supramolecular nanostructures with various morphology. [38,39] Although there have been successful examples of pH-responsive peptide self-assembly, most systems require a custom-design approach through fine-balancing the number of acidic and basic residues in the solvent-exposed region.…”

“…Recent advances in the mechanistic understanding of peptide self‐assembly further promote the development of hierarchical peptide self‐assembly with long‐range ordering [26,27] . Amino acids with an ionizable side chain, such as lysine or glutamic acid have been commonly selected and placed in a hydrophilic domain of a synthetic peptide to control the pH‐dependent self‐assembly process [6,9,28–37] . In particular, recently it was discovered that by judicious selection of amino acid building blocks, pH‐responsive peptides can form supramolecular nanostructures with various morphology [38,39] .…”

Effective Treatment of Helicobacter pylori Infection Using Supramolecular Antimicrobial Peptide Hydrogels

“…The mechanical strength of the pH 10 hydrogel was slightly reduced compared with that of the pH 7 hydrogel as revealed by the rheological results (Figure e,f). This is likely due to the partial breakage of nanofibers (Supporting Information, Figure S2) because the lysine-rich C 12 G 2 molecule is close to the isoelectric point at high pH with the results of charge screening …”

Biological preparation and characterization of surfactant‐like peptides

“…Based on the structure, the application value of surfactant‐like peptides can be explored. It was shown that surfactant‐like peptides with this structure have self‐assembly properties at different pH (Zhang et al, 2020). Moreover, as an antibacterial peptide, it showed antibacterial activity against Gram‐negative E. coli and Gram‐positive Staphylococcus aureus (Chen et al, 2010).…”