Self-assembly and structure transformations in living polymers forming fibrils |
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Authors: | IA Nyrkova AN Semenov A Aggeli M Bell N Boden TCB McLeish |
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Institution: | (1) Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, UK, GB;(2) Centre for Self-Organising Molecular Systems, University of Leeds, Leeds LS2 9JT, UK, GB |
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Abstract: | The classical isodesmic one-dimensional model for equilibrium polymerization is generalized in order to describe self-assembly
in systems forming fibrils. The model was applied to peptide solutions forming -sheet tapes which can further aggregate into stacks of various thickness: double tapes and fibrils (several double tapes
stacked together). We found that in some cases the model yields several step-like transitions as the concentration increases:
first from monomers to single or double tapes, and then to fibrils. The abruptness of the first transition is controlled by
the free energy penalty for transformation of a peptide from random coil to a straight -strand conformation (the latter is characteristic for tapes). If both single and double tapes are allowed, the length of
the aggregates after the first transition can be very large with high scission energies. For very low energies of attraction
between double tapes, the transition from double tapes to fibrils happens separately (above the first transition), and it
is even more abrupt and produces extremely long fibrils. The theoretical findings are used to extract the characteristic molecular
parameters for the self-assembly of the de
novo peptide DN1 forming polymeric -sheets in water.
Received 28 June 1999 |
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Keywords: | PACS 36 20 Ey Conformation (statistics and dynamics) - 61 46 +w Clusters nanoparticles and nanocrystalline materials - 87 15 -v Biomolecules: structure and physical properties |
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