α Helix Unwinding as Force Buffer in Spectrins. Spectrins are cytoskeletal proteins located at the inner face of the plasma membrane, making connections between membrane anchors and the actin cortex, and between actin filaments. Spectrins share a common structure forming a bundle of 3 α-helices and play a major role during cell deformation. Here, we used high-speed force spectroscopy and steered molecular dynamics simulations to understand the mechanical stability of spectrin, revealing a molecular force buffering function. We find that spectrin acts as a soft spring at short extensions (70−100 Å). Under continuous external stretching, its α-helices unwind, leading to a viscous mechanical response over larger extensions (100−300 Å), represented by a constant-force plateau in force/extension curves. This viscous force buffering emerges from a quasi-equilibrium competition between disruption and reformation of α-helical hydrogen bonds. Our results suggest that, in contrast to β-sheet proteins, which unfold in a catastrophic event, α-helical spectrins dominantly unwind, providing a viscous force buffer over extensions about 5 times their folded length. ACS Nano, 2018.

Recent publications

Water-Controlled Switching in Rotaxanes
Shuangli Du; Haohao Fu; Xueguang Shao; Christophe Chipot; Wensheng Cai;
The Journal of Physical Chemistry C (2018) 122 (16): 9229-9234

Accurate Estimation of the Standard Binding Free Energy of Netropsin with DNA
Hong Zhang; Hugo Gattuso; Elise Dumont; Wensheng Cai; Antonio Monari; Christophe Chipot; Francois Dehez;
Molecules (2018) 23 (2): 129-
BFEE: A User-Friendly Graphical Interface Facilitating Absolute Binding Free-Energy Calculations
Haohao Fu; James C. Gumbart; Haochuan Chen; Xueguang Shao; Wensheng Cai; Christophe Chipot;
Journal of Chemical Information and Modeling (2018) 58 (3): 556-560


- Renewal of the Laboratoire International Associé CNRS-University of Illinois at Urbana-Champaign on November 2016
- An update of ParseFEP is available in the latest version of VMD.
- 新的分子动力学讲义 (Dissemination).


Laboratoire International Associé
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