Hierarchical Self-Assembly of Peptide Molecules

The self-assembly of peptides leading to 3D structures is a hierarchical process (simplified shown in Fig. 5.25). 

Peptide self-assembly nano fiber formation 

FIGURE 5.25 Simplified schematic illustrations of the hierarchical self-assembly processes involved in the formation of hydrogels from peptide molecules. Source Dasgupta et al. [55]. Reproduced with permission from the Royal Society of Chemistry. 

In solution, peptide molecules adopt a specific secondary conformation, like P-sheet, P-hairpin, a-helix, or the coiled coil (Fig. 5.26). The secondary structures then self-assemble to form nanofibers or physically cross-linked networks. Elongation of the nanofibers in 3D space leads to thicker and longer fibers, which further assemble to fibrillar networks capable of entrapping water (Fig. 5.25) [55]. P-Structured peptides dominate the literature of self-assembled systems, either natural or designed. 

The folding and the hierarchical self-assembly processes are governed by hydrophobic interaction, tc-tc stacking, hydrogen bonding, and electrostatic interaction. Natural amino acids provide all fundamental features that promote these types of intra- or intermolecular interactions. 

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