A polyclonal antibody against the quinolone drug pazufloxacin (PAZ) but with surprisingly broad specificity was raised to simultaneously detect 24 quinolones (QNs). The developed competitive indirect enzyme-linked immunosorbent assay (ciELISA) exhibited limits of detection (LODs) for the 24 QNs ranging from 0.45 to 15.16 ng/mL, below the maximum residue levels (MRLs). To better understand the obtained broad specificity, a genetic algorithm with linear assignment of hypermolecular alignment of data sets (GALAHAD) was used to generate the desired pharmacophore model and superimpose the QNs, and then advanced comparative molecular field analysis (CoMFA) and advanced comparative molecular similarity indices analysis (CoMSIA) models were employed to study the three-dimensional quantitative structure-activity relationship (3D QSAR) between QNs and the antibody. It was found that the QNs could interact with the antibody with different binding poses, and cross-reactivity was mainly positively correlated with the bulky substructure containing electronegative atom at the 7-position, while it was negatively associated with the large bulky substructure at the 1-position of QNs.
Keywords: QSAR; broad specificity; immunoassay; pazufloxacin; quinolone.