This article proposes a new approach to the modeling of the molecular-level mechanism of ligand–receptor interaction for Ca² receptor binding site. Chemically induced dynamic nuclear polarization (CIDNP) technique has been used to unravel fine details of the reaction in the model system composed of one of the known Ca² antagonist drugs, nifedipine (NF), and isolated amino acid residuals (e.g. tyrosine [Tyr]) of Ca² receptor binding site. It has been conclusively demonstrated that the reaction between NF and Tyr resulting in the oxidation product—nitroso form of NF—obeys the radical mechanism. CIDNP data in combination with the results of mathematical modeling of the structures of ligand–receptor complexes have allowed to propose the mechanism of the interaction of NF with Ca² receptor binding site.