Tuning chelation by the surfactant-like peptide A6H using predetermined pH values

Area of Science:

• Materials Science
• Biochemistry
• Nanotechnology

Background:

• Peptide self-assembly is crucial for developing novel nanomaterials.
• Histidine-containing peptides can chelate metal ions, influencing assembly.
• Understanding pH-dependent behavior is key for controlled nanomaterial fabrication.

Purpose of the Study:

• To investigate the self-assembly of the peptide A6H (hexa-alanine with histidine) under varying pH conditions.
• To examine the role of Zn(2+) ion chelation in A6H self-assembly.
• To determine how solution pH affects both the self-assembly morphology and metal ion binding sites of A6H.

Main Methods:

• Studied self-assembly of A6H in ZnCl2 solutions across acidic and neutral pH.
• Analyzed the structures formed using techniques not explicitly stated but implied by structural descriptions (e.g., microscopy, spectroscopy).
• Investigated the chelation sites of Zn(2+) by A6H under different pH conditions.

Main Results:

• In acidic solutions, A6H self-assembles into nanotapes via β-sheet structures.
• Zn(2+) chelation by carbonyl oxygens in acidic conditions lowers the onset concentration for nanotape formation.
• In neutral solutions, A6H forms short sheets or pseudocrystalline tapes, with the imidazole ring chelating Zn(2+).

Conclusions:

• Solution pH significantly alters the self-assembly pathways and Zn(2+) chelation sites of A6H.
• The amphiphilic nature of A6H appears to dictate the internal structure of self-assembled aggregates regardless of pH-induced chelation changes.
• Controlled pH environments offer a method to tune the self-assembly and properties of histidine-containing peptides.