Mechanical Unfolding of Titin I27 Domain: Nanoscale Simulation of Mechanical Properties Based on Virial Theorem via Steered Molecular Dynamics Technique

Abstract

The mechanical properties of a single titin immunoglobulin-like domain (I27) are studied based<br><br> on the Virial stress definition via steered molecular dynamics simulation. Moreover, the effects<br><br> of biological conditions on the obtained results are investigated. Due to different viewpoints on<br><br> the Virial stress definition, the role of the kinetic stress in the Virial stress definition is<br><br>elucidated. The obtained Young’s modulus is about GPa. It is found that the ultimate<br><br> stress decreases nonlinearly and the Young’s modulus decreases almost linearly with an increase<br><br> in temperature. It is observed that the mechanical properties decrease with a decrease in the<br><br> strain rate. The mechanical properties are not sensitive to small unfolding forces, but they rise up<br><br> with an increase in the force magnitude afterward. Considering the kinetic stress term in<br><br>calculation of the Virial stress increases the accuracy of the results, but does not have a<br><br>significant effect on mechanical properties especially at low temperatures. This implies that the<br><br> kinetic stress term can be ignored at low temperatures. This study furnishes a basis for the I27<br><br> domain where the mechanical properties must be taken into account.