The geometries of seventeen sulfonamide molecules were optimized using a quantum chemistry AM1 method and the minimum conformations of these molecules obtained. Some important parameters including conformational properties (bond length, bond angle and dihedral), electronic parameters (the electric amount of R group and other important atoms) and physico-chemical parameters (hydration energy, Log P values), were calculated to compare the difference among the 17 sulfonamides and subsenquently the recognition between four polyclonal antibodies to sulfamethazine and sulfonamides structurally related analogs was disscussed. The results show that the hydration energy and Log P values have the most impotant role in the structure-activity relationship between the antibody and sulfonamides, whereas, the conformational and electronic parameters exert limited influence on the relationship.

Key words: sulfonamide, polyclonal antibody, molecular modeling, quantum chemistry, structure-activity relationship