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Journal of Biological Sciences
  Year: 2005 | Volume: 5 | Issue: 6 | Page No.: 744-758
DOI: 10.3923/jbs.2005.744.758
Modulation of Dissociation Kinetics by External Force: Examination of the Bell Model
Valentine I. Vullev

Abstract:
Force techniques have been extensively used for studying interactions between macromolecules of biological importance. Bell model, which shows the force influence on the dissociation rates, ln(k(F))=ln(k(0))+ F(kBT) 1, has been broadly employed for analysis of force-modulated kinetics. This linear relationship, however, is an approximation. Herein, the conditions for applicability of the Bell model were examined for dissociation processes that proceed through no more than one transition state. The findings show that: (1) the slopes and the intercepts obtained from the linear analyses depend on the force ranges within which the curve fittings are performed; (2) broadening of the force range of analysis compromises the linear approximation provided by Bell model; (3) linear analysis tends to over estimate the values of the dissociation rate constants at zero force, k(0) and (4) limiting the linear analysis to relatively weak forces produces values for k(0) that were close to the expected real values of the rate constant. An alternative interpretation of the slopes and the intercepts obtained from the linear analyses is described. The parameter was ascribed to the average separation between the associated and transition states along the reaction pathway within the force range of the linear analysis. The latter was contrary to the broadly accepted view that represents the distance between the associated and transition states in the absence of external force. In addition, rather than assigning them to the zero-force activation energy, the intercepts obtained from the linear fits were ascribed to the coordinate-average energies that are differences in the potential energy along the trajectory of dissociation in the absence of external force. These alternative assignments of the linear parameters can prove useful in applications of Bell model for mapping trajectories and landscapes of dissociation processes.
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How to cite this article:

Valentine I. Vullev , 2005. Modulation of Dissociation Kinetics by External Force: Examination of the Bell Model. Journal of Biological Sciences, 5: 744-758.

DOI: 10.3923/jbs.2005.744.758

URL: https://scialert.net/abstract/?doi=jbs.2005.744.758

 
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