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Issue 21, 2012
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Unzipping the role of chirality in nanoscale self-assembly of tripeptide hydrogels

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Abstract

Change of chirality is a useful tool to manipulate the aqueous self-assembly behaviour of uncapped, hydrophobic tripeptides. In contrast with other short peptides, these tripeptides form hydrogels at a physiological pH without the aid of organic solvents or end-capping groups (e.g. Fmoc). The novel hydrogel forming peptide DLeu-Phe-Phe (DLFF) and its epimer Leu-Phe-Phe (LFF) exemplify dramatic supramolecular effects induced by subtle changes to stereochemistry. Only the D-amino acid-containing peptide instantly forms a hydrogel in aqueous solution following a pH switch, generating long fibres (>100 μm) that entangle into a 3D network. However, unexpected nanostructures are observed for both peptides and they are particularly heterogeneous for LFF. Structural analyses using CD, FT-IR and fluorescent amyloid staining reveal anti-parallel beta-sheets for both peptides. XRD analysis also identifies key distances consistent with beta-sheet formation in both peptides, but suggests additional high molecular order and extended molecular length for DLFF only. Molecular modelling of the two peptides highlights the key interactions responsible for self-assembly; in particular, rapid self-assembly of DLFF is promoted by a phenylalanine zipper, which is not possible because of steric factors for LFF. In conclusion, this study elucidates for the first time the molecular basis for how chirality can dramatically influence supramolecular organisation in very short peptide sequences.

Graphical abstract: Unzipping the role of chirality in nanoscale self-assembly of tripeptide hydrogels

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Publication details

The article was received on 25 Jul 2012, accepted on 10 Aug 2012 and first published on 15 Aug 2012


Article type: Paper
DOI: 10.1039/C2NR32006A
Citation: Nanoscale, 2012,4, 6752-6760
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    Unzipping the role of chirality in nanoscale self-assembly of tripeptide hydrogels

    S. Marchesan, L. Waddington, C. D. Easton, D. A. Winkler, L. Goodall, J. Forsythe and P. G. Hartley, Nanoscale, 2012, 4, 6752
    DOI: 10.1039/C2NR32006A

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