  Protein-peptide interactions play essential roles in many cellular processes
and their structural characterization is the major focus of current
experimental and theoretical research. Two decades ago, it was proposed to
employ the steered molecular dynamics to assess the strength of protein-peptide
interactions. The idea behind using steered molecular dynamics simulations is
that the mechanical stability can be used as a promising and an efficient
alternative to computationally highly demanding estimation of binding affinity.
However, mechanical stability defined as a peak in force-extension profile
depends on the choice of the pulling direction. Here we propose an uncommon
choice of the pulling direction along resultant dipole moment vector, which has
not been explored in simulations so far. Using explicit solvent all-atom MD
simulations, we apply steered molecular dynamics technique to probe mechanical
resistance of protein-peptide system pulled along two different vectors. A
novel pulling direction, along the resultant dipole moment vector, results in
stronger forces compared to commonly used peptide unbinding along center of
masses vector. Our results demonstrate that resultant dipole moment is one of
the factors influencing the mechanical stability of protein-peptide complex.
