Early potential evaluation of lead compounds from a DNA-encoded library by the determination of their thermodynamics through a chromatographic method based on immobilized β₂-adrenoceptor

Early potential evaluation of lead compounds is critical to decrease downstream lead-optimization cycle times and clinical attrition rates for drug development. This increasingly necessitates the methodologies for accurately evaluating the potential compounds. This work immobilized β₂-adrenoceptor (β₂-AR) onto microspheres through Halo-tag mediated reaction. Characterizing the resulting microspheres by elemental and functional analysis, we utilized the immobilized receptor to determine the thermodynamics of terbutaline, tulobuterol, clorprenaline, salbutamol, and methoxyphenamine. The association constants correlated to their capacity factors on the column containing the immobilized β₂-AR, thus providing a possibility for early potential evaluation of lead compounds from complex matrices like a DNA-encoded library. By this model, the lead compound (XC267) was predicted to have an association constant higher than terbutaline, salbutamol, and methoxyphenamine, but lower than tulobuterol and clorprenaline. The binding interaction between XC267 and β₂-AR is a spontaneous endothermic process with an association constant of (6.62 ± 0.13) × 10⁴ M^-1 at 37 °C. The change of Gibbs free energy(ΔG^θ), enthalpy change (ΔH^θ), and entropy change (ΔS^θ) was -28.49 kJ/mol, -10.58 kJ/mol, and 57.79 J/moL·K at 37 °C. By the semi-empirical rule of Ross, the driving force of the interaction between XC267 and β₂-AR was electrostatic interaction. Such binding force was also achieved by molecular docking. These results suggested that XC267 is a candidate to treat asthma by specific binding to β₂-AR. We reasoned that receptor chromatography is able to the early potential evaluation of lead compounds from complex matrices.