Jamming proteins with slipknots and their free energy landscape

TL;DR

This study investigates how slipknots in proteins influence their unfolding behavior under force, revealing a complex energy landscape with metastable states that affect unfolding times.

Contribution

It provides a detailed theoretical and simulation-based analysis of slipknot proteins, including the free energy landscape and the role of metastable states in unfolding.

Findings

Unfolding times grow unexpectedly at certain force thresholds.

Existence of metastable jammed slipknot configurations.

Simulation results support analytical predictions of the free energy landscape.

Abstract

Theoretical studies of stretching proteins with slipknots reveal a surprising growth of their unfolding times when the stretching force crosses an intermediate threshold. This behavior arises as a consequence of the existence of alternative unfolding routes that are dominant at different force ranges. Responsible for longer unfolding times at higher forces is the existence of an intermediate, metastable configuration where the slipknot is jammed. Simulations are performed with a coarsed grained model with further quantification using a refined description of the geometry of the slipknots. The simulation data is used to determine the free energy landscape (FEL) of the protein, which supports recent analytical predictions.