Role of pulling direction in understanding the energy landscape of proteins

TL;DR

This paper investigates how pulling direction affects the energy landscape of proteins using lattice models, revealing that force direction influences unfolding mechanisms and transition types.

Contribution

It introduces an analytical and numerical study of anisotropic lattice models to understand the impact of pulling direction on protein unfolding.

Findings

Force-temperature diagrams vary with pulling direction.

Unzipping or shearing transitions dominate depending on force direction.

Unfolding dynamics are direction-dependent.

Abstract

Single molecule force spectroscopy provide details of the underlying energy surfaces of proteins which are essential to the understanding of their unfolding process. Recently, it has been observed experimentally that by pulling proteins in different directions relative to their secondary structure, one can gain a better understanding of the shape of the energy landscape. We consider simple lattice models which are anisotropic in nature to study the response of a force in unfolding of a polymer. Our analytical solution of the model, supported by extensive numerical calculations, reveal that the force temperature diagrams are very different depending on the direction of the applied force. We find that either unzipping or shearing kind transitions dominate the dynamics of the unfolding process depending solely on the direction of the applied force.