Single chain force spectroscopy - Reading the sequence of HP protein models |
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Authors: | N-K Lee TA Vilgis |
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Institution: | (1) Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, DE |
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Abstract: | We study the elastic properties of single A/B random copolymer chains, with a specific sequence and use them as theoretical
model for so called HP proteins. HP proteins carry hydrophilic (P) and hydrophobic (H) monomers. We predict a rich structure
in the force-extension relations which can be attributed to the information in the sequence. The variational method is used
to probe local minima on the path of stretching and releasing for the chain molecules. At a given force, we find multiple
configurations which are separated by energy barriers. A collapsed globular configuration consists of several domains which
unravel cooperatively. Upon stretching, the unfolding path shows a stepwise pattern corresponding to the unfolding of each
domain. While releasing, several cores can be created simultaneously in the middle of the chain, resulting in a different
path of collapse. The long-range interactions and stiffness of the chain simplify the potential landscape given by the disorder
in sequence.
Received 5 March 2002 / Received in final form 16 May 2002 Published online 13 August 2002 |
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Keywords: | PACS 36 20 Fz Constitution (chains and sequences) – 87 15 Da Physical chemistry of solutions of biomolecules condensed states – 87 15 -v Molecular biophysics |
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