The study of ligand-receptor interactions through computational techniques, such as molecular dynamics (MD) and docking, has several limitations due to their temporal and spatial dimensions. Docking can reasonably identify the pose and energy of interaction but cannot distinguish between agonist and antagonist. MD allows us to collect useful information on the thermodynamics and kinetics of the whole system, but a method is needed to extract information on receptor activity. In this work, we extracted the dihedral angles of the receptor backbone and the RMSD of each residue during a dynamic of 20 ns. We used Sysa coding to reduce the information of the entire receptor system to a collection of strings, one for each snapshot of the dynamics. The strings are compared with an alignment-free approach and a distance calculated for each one. The comparison of distances makes it possible to discriminate against the overall agonist-antagonist behavior. The FFAR1 system, the free fatty acid receptor 1, of which some crystallographic structures of agonists and antagonists are available, will be shown as an example.