Role of conformational entropy in force-induced bio-polymer unfolding

Sanjay Kumar 1, Iwan Jensen 2, Jesper L. Jacobsen 3, Anthony J. Guttmann 2

Physical Review Letters 98 (2007) 128101

A statistical mechanical description of flexible and semi-flexible polymer chains in a poor solvent is developed in the constant force and constant distance ensembles. We predict the existence of many intermediate states at low temperatures stabilized by the force. A unified response to pulling and compressing forces has been obtained in the constant distance ensemble. We show the signature of a cross-over length which increases linearly with the chain length. Below this cross-over length, the critical force of unfolding decreases with temperature, while above, it increases with temperature. For stiff chains, we report for the first time 'saw-tooth' like behavior in the force-extension curves which has been seen earlier in the case of protein unfolding.

  • 1. Department of Physics,
    Banaras Hindu University
  • 2. ARC Centre of Excellence for Mathematics and Statistics of Complex Systems, Department of Mathematics and Statistics,
    The University of Melbourne
  • 3. Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS),
    CNRS : UMR8626 – Université Paris XI - Paris Sud