The prediction of a protein structure, starting from the amino acid sequence, turns to be very challenging and was deeply investigated over the years. Concerning this, in the past were reported very significant outcomes, as the thermodynamic hypothesis and the driving forces of the folding process . In 2019 it was described a survey which focuses on the amino acid sequence to calculate the structure of two peptides (Leu-enkephalin and calcitonin) and is based on the development of the main mechanical forces (MMFs) arising from the chemical interactions among the residues side chains. Anyway, concerning the calculations, the latter study showed some limits on the definition of the degrees of freedom (now twisting constant) so that, this problem was further investigated in order to enunciate rules to define univocally the twisting constants and the threshold distances for the chemical interactions to occur. In this context, the present study realized on the DNA binding domain of the γ δ resolvase (PDB code: 1res) , aims to establish rules that allow to predict and calculate the backbone dihedral angles φ, so that, combined with the previous study , could furnish a theoretical method to predict the structure of peptides and proteins starting from the amino acid sequence. This study is focused on the chemical interactions developed amongst the side chains of the residues and these were considered to be the informations required to fold the polypeptide. The survey shows a good agreement between the calculated and the experimentally determined values, thus the method presented, combined to the previous , reveals to be an efficient approach to predict at least the backbone dihedral angles φ starting from the amino acid sequence.