posted on 2023-11-29, 21:30authored byQiushi Jin, Yuhang Fan, Tong He, Junling Peng, Jing Liu, Jianping Wang
A recognition motif is vital in determining the specificity
and
sensitivity of the fluorescence polarization assay (FPA) for detecting
chemical contaminants in food. Four candidates (Gyrase, GyrBA, TopIV,
and QepA) were prepared for this study. The applicability of QepA
was confirmed through DNA cleavage assay, inhibition effects, and
mechanism investigations using molecular docking, compared to other
counterparts. Finally, a novel FPA based on QepA and a CIP-FITC tracer
for the detection of fluoroquinolones (FQs) in eggs was developed.
The limits of detection (LODs) for eight fluoroquinolones ranged from
2.2 to 5.1 ng g–1, with enrofloxacin, danofloxacin,
and difloxacin meeting the maximum residue limits (MRLs). The spiked
recoveries ranged from 65.8 to 103.6% with coefficients of variation
(CVs) of 5.4–12.8%. Therefore, a new recognition motif for
FQs that did not belong to conventional antibodies was identified,
and QepA-based FPA could be a potential tool for rapid, homogeneous,
and sensitive monitoring of the residue of FQs in eggs.