Can re-entrance be observed in force-induced transitions?Sanjay Kumar
Department of Physics, Banaras Hindu University - Varanasi 221 005, India
received 6 May 2008; accepted in final form 9 January 2009; published February 2009
published online 9 February 2009
A large conformational change in the reaction co-ordinate and the role of the solvent in the formation of base pairing are combined to settle a long-standing issue, i.e. prediction of re-entrance in the force-induced transition of DNA. A direct way to observe the re-entrance, i.e. a strand that goes to the closed state from the open state and again to the open state with increasing temperature, appears difficult to be achieved in the laboratory. An experimental protocol (in direct way) in the constant force ensemble is being proposed for the first time that will enable the observation of the re-entrance behavior in the force-temperature plane. Our exact results for a small oligonucleotide that forms a hairpin structure provide the evidence that re-entrance can be observed.
82.35.Jk - Copolymers, phase transitions, structure.
36.20.Ey - Conformation (statistics and dynamics).
64.90.+b - Other topics in equations of state, phase equilibria, and phase transitions.
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