Effects of intermediate bound states in dynamic force spectroscopy.
We revisit some aspects of the interpretation of dynamic force spectroscopy experiments. The standard theory predicts that the typical unbinding force f* is linearly proportional to the logarithm of the loading rate r when a single energy barrier controls the unbinding process. For a more complex situation of N barriers, it predicts at most N linear segments for the f* vs. log(r) curve, each segment characterizing a different barrier. Here we extend this existing picture using a refined approximation, provide a more general analytical formula, and show that in principle up to N(N + 1) / 2 segments can show up experimentally. As a consequence, the determination of the positions and even the number of the energy barriers from the experimental data can be ambiguous. A further possible consequence of a multiple-barrier landscape is a bimodal or multimodal distribution of the unbinding force at certain loading rates, a feature recently observed experimentally.
Derényi
Imre
I
Department of Biological Physics, Eötvös University, H-1117 Budapest, Hungary. derenyi@elte.hu
Bartolo
Denis
D
Ajdari
Armand
A
D001665:Binding Sites; D001704:Biopolymers / Q000737:chemistry*; D003198:Computer Simulation; D004548:Elasticity; D007700:Kinetics; D008846:Micromanipulation / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D013314:Stress, Mechanical
D001704:Biopolymers