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Structure and dynamics of self-assembling beta-sheet peptide tapes by dynamic light scattering
A Aggeli1, G Fytas, D Vlassopoulos
1Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (FORTH), P.O.Box 1527, 71110 Heraklion, Crete, Greece. a.aggeli@chem.leeds.ac.uk
Biomacromolecules
|December 26, 2001
Summary
Self-assembling peptide K24 forms beta-sheet tapes in solution, behaving as semiflexible chains. These tapes form large-mesh networks and physical gels, exhibiting unique concentration-dependent properties distinct from conventional polymers.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Biophysics
Background:
- Oligomeric peptides can self-assemble into one-dimensional beta-sheet tapes.
- Previous theoretical models predicted coinlike structures for tapelike polymers in solution.
Purpose of the Study:
- To systematically investigate the size, shape, dynamics, and interactions of K24 beta-sheet tapes.
- To explore the behavior of these tapes across a wide range of concentrations (10(-7)-1 mM).
Main Methods:
- Photon correlation spectroscopy was employed for the investigation.
- Polarized q-dependent light-scattering intensity was analyzed.
- Concentration-dependent measurements were performed.
Main Results:
- K24 beta-sheet tapes behave as semiflexible chains with persistence lengths of several hundred nanometers.
- Light scattering revealed tape dimensions consistent with prolate objects (major axis ~630 nm, minor axis ~40 nm), contrary to theoretical predictions.
- At higher concentrations, tapes form networks with large mesh sizes, transitioning to a physical gel at approximately 0.4 mM.
Conclusions:
- The observed prolate shape is attributed to the pronounced twist and bend of the beta-tapes.
- The network of entangled tapes exhibits unique concentration-dependent scaling properties, approximating semirigid polymers.
- The study provides the first systematic investigation into the physical behavior of these self-assembling peptide tapes.