Transient-state fluctuationlike relation for the driving force on a biomolecule

Tsallis statistics generalization of nonequilibrium work relations

Nonequilibrium work relations such as Jarzynski equality and Crooks fluctuation theorem relate the free energy differences between two equilibrium states and the work distribution of nonequilibrium processes. We use the third constraint formulation of Tsallis statistics and derive the q-statistics generalization of nonequilibrium work relations.

Force fluctuations in stretching a tethered polymer

The recently proposed fluctuation relation in unfolding forces [Phys. Rev. E 84, 060101(R) (2011)] is reexamined taking into account the explicit time dependence of the force distribution. The stretching of a tethered Rouse polymer is exactly solved and the ratio of the probabilities of positive to negative forces is shown to be an exponential in force. Extensive steered molecular dynamics simulations of unfolding of deca alanine peptide confirm the form of fluctuation relation proposed earlier, but with explicit correct time dependence of unfolding forces taken into account. From exact calculations and simulations, a linear dependence of the constant in the exponential of the fluctuation relation on average unfolding forces and inverse temperature is proposed.

Comment on "transient-state fluctuationlike relation for the driving force on a biomolecule"

Two analytically tractable systems, Brownian particles in (i) moving harmonic oscillator or (ii) with a time-dependent natural frequency, obey a force fluctuation theorem similar to that proposed by Ponmurugan and Vemparala [Phys. Rev. E 84, 060101(R) (2011)]. Many of their results can be explained by using the former case as a model.