COMPUTATIONAL SIMULATIONS OF ANTIBODY: ANTIGEN UNBINDING

The unbinding process of the mAb4–4–20:fluorescein complex was investigated by means of a computational approach at the atomistic classical mechanical level, probing only a relevant set of generalized coordinates in order to determine the putative dissociation paths of the system. The complex problem was reduced to a low-dimensional scanning along a selected distance between the protein and the escaping ligand. The unbinding was further characterized by assessing the relative positional and orientational coordinates of the ligand. Solvent effects were accounted for by means of the Poisson–Boltzmann continuum model. The complex's dissociation time was derived from the calculated barrier height, in compliance with the experimentally reported Arrhenius-like behavior. The computed results are in good agreement with the available experimental data.