Biophysical Society Thematic Meeting - October 25-30, 2015

Polymers and Self Assembly: From Biology to Nanomaterials Poster Session I

4-POS Board 4 Self-Assembly Pathway of Peptide Nanotubes Formed by a Glutamatic Acid-Based Bolaamphiphile Wendel Alves 1 , Emerson R. Silva 1 , Valeria Castelletto 2 , Mehedi Reza 3 , Janne Ruokolainen 3 , Rohanah Hussain 4 , Ian W. Hamley 2 . 1 Universidade Federal do ABC, Santo André, São Paulo, Brazil, 2 University of Reading, Reading, Berkshire, United Kingdom, 3 Aalto University School of Science, FI-00076, Finland, 4 Diamond Light Source Ltd, Didcot, United Kingdom. The self-assembly of peptide-nanotubes formed by an L-glutamic acid-based bolaamphiphile is shown to proceed via a remarkable mechanism where the peptide conformation changes from b- sheet to unordered. The kinetics of this process are elucidated via X-ray scattering and UV circular dichroism methods. The reverse transition from ‘‘unordered’’ to b-sheet structures is triggered by UV radiation [1]. Here, we use small-angle X-ray scattering (SAXS) and synchrotron radiation circular dichroism (SRCD) to examine the structure and the self-assembly pathway of an amino acid-based bolaamphiphile, the linear octamer EFL4FE (E = L-glutamic acid, F = L-phenylalanine and L = L-leucine). The hydrophobic region of the sequence is composed of four leucine repeats, an aliphatic amino acid often found in molecular zippers in protein aggregates. This aliphatic core is complemented by two phenylalanine moieties which are designed to assist lateral association due to p–p stacking interactions between aromatic rings. The polar heads are made from L-glutamic acid moieties endowed with carboxyl groups. We found a remarkable and unexpected pathway of nanotube formation in which initial b-sheet structures are disrupted. Reference: [1] Silva, E.R.S.; Alves, W.A.; Castelletto, V.; Reza, M.; Ruokolainen, J.; Hussain, R.; Hamley, I.W. Chem. Commun. DOI: 10.1039/c5cc03640b .

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