The effect of pulling geometry and concatamer architecture on the mechanical unfolding force of β-sheet proteins
Abstract
The molecular origins of mechanical resistance in proteins are still unclear, although the orientation of secondary structural elements relative to the applied force vector is thought to play an important role. By using a novel method of protein immobilisation that allows force to be applied to the same all β-protein, E2lip3, in two different directions, we show that the energy landscape for mechanical unfolding is remarkably anisotropic. These results, in combination with molecular dynamics simulations, reveal that the unfolding pathway depends on pulling geometry, leading to unfolding forces that differ by an order of magnitude. We also demonstrate how, for a given pulling direction, kinetic effects lead to apparent unfolding forces that depend on the number of domains being unfolded and the overall compliance. Hence, the mechanical resistance of a protein is not solely endowed by sequence, topology or unfolding rate constant, but depends critically on the direction of the applied extension.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MAR.S9006O