Quantum-Chemical Simulation of Binding between Molecules as a Technique for Estimation of the Probability for Ligand − Receptor Complexification of Comenic Acid

Using computer simulation of the binding between molecules of opioid ligands and key amino acids in the macromolecule of an opioid receptor, we calculated the enthalpies of binding. Negative values of enthalpies substantiated conclusions on the high probability of such binding, while positive enthalpies were indicative of the low probability of this process binding. We found that the enthalpy of binding of comenic acid with asparagine is +17.5, of comenic acid with tryptophan is −8.7, and of comenic acid with lysine is −27.6 kcal/mol. We conclude that comenic acid binds only with the sites of selectivity but not with all sites of the opioid receptor.