Force-Clamp Experiments Reveal the Free-Energy Profile and Diffusion Coefficient of the Collapse of Protein Molecules

作者：Lannon H^*; Haghpanah J S; Montclare J K; Vanden Eijnden E; Brujic J

来源：Physical Review Letters, 2013, 110(12): 128301.

DOI：10.1103/PhysRevLett.110.128301

We present force-clamp data on the collapse of ubiquitin polyproteins from a highly extended state to the folded length, in response to a quench in the force from 110 pN to 5 or 10 pN. Using a recent method for free-energy reconstruction from the observed nonequilibrium trajectories, we find that their statistics is captured by simple diffusion along the end-to-end length. The estimated diffusion coefficient of similar to 100 nm(2) s(-1) is significantly slower than expected from viscous effects alone, possibly because of the internal degrees of freedom of the protein. The free-energy profiles give validity to a physical model in which the multiple protein domains collapse all at once and the role of the force is approximately captured by the Bell model. DOI: 10.1103/PhysRevLett.110.128301

• 出版日期2013-3-22