The influence of amino acid sequence on structure and morphology of polydiacetylene containing peptide fibres

Abstract

A systematic study was performed on the influence of charge and steric hindrance on the assembly into fibres of a series of pentameric peptides based on the well-known β-sheet forming sequence Gly-Ala-Gly-Ala-Gly, which were N-terminally acylated with pentacosadiynoic acid. To investigate the effect of steric hindrance and charge repulsion on the fibre structure, either the N-terminal or the C-terminal amino acid in the sequence was replaced by a glutamic acid or lysine residue. Furthermore, peptide amphiphiles (PAs) with an amide or a free acid group at the C-terminus were compared. Steric hindrance and charge repulsion were addressed individually by varying the pH during and after fibre preparation. The self-assembled structures were examined with circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). UV spectroscopy was used to probe the diacetylene packing in the hydrophobic tail, both by polymerisation behaviour and chromatic properties of the polymers. In brief, the assembly was hindered more if the modification was close to the alkyl tail, and glutamic acid brought about a larger effect than lysine. PAs with two charges yielded assemblies which after polymerisation were found to be the most susceptible towards changes in pH, behaving as a colour-based pH sensor. Typically, TEM and UV showed the same trends, indicating that a distorted morphology as observed with TEM is indicative of a poorer molecular packing of the peptide amphiphile fibres, probed via the changes in absorption of the polydiacetylene backbone.

Patterning of Soft Matter across Multiple Length Scales

“…In water, both 1a and 1b form 1D rodlike aggregates, which are isotropically distributed over the sample (Figure 1 b,c). [ 45,46 ] In aqueous solutions, 2 self-assembles through hydrophobic shielding and hydrogen-bonding interactions, forming micron to millimeter long-twisted beta-sheet fi bers (Figure 1 d). [ 45,46 ] In aqueous solutions, 2 self-assembles through hydrophobic shielding and hydrogen-bonding interactions, forming micron to millimeter long-twisted beta-sheet fi bers (Figure 1 d).…”

Nanoporous Conducting Covalent Organic Polymer (COP) Nanostructures as Metal-Free High Performance Visible-Light Photocatalyst for Water Treatment and Enhanced CO2 Capture

“…57 The influence of amino acid sequences on the structure and morphology of the peptide functionalized polydiacetylene backbone is also reported. The prerequisite of the β-sheet structure by peptide functionalized diacetylene to undergo photopolymerization reaction is reported by Stupp et al 58 The role of dipeptide sequences in dipeptide functionalized polydiacetylenes on unusual chromatic behavior was studied in detail by Leblanc et al 59 Viscoelastic properties of compound 1 organogel were explored by rheological measurements. Rheological measurements of self-supporting toluene gel formed by compound 1 were performed with a dynamic frequency sweep at a constant strain of 0.05%.…”

Reverse-engineered Silk Hydrogels for Cell and Drug Delivery

“…The transition times for the establishment of secondary structure and morphology revealed that the motifs responsible for β-sheet formation were GS6 > GS10 > GY8 > GY6 [71]. Silk self-assembly has inspired the design of synthetic self-assembling peptides [72][73][74] and proteins to generate 'silkmimetic' hydrogels (reviewed in [75]).…”