Identification of Binding Epitopes of a Fluorinated Compound Bound to Proteins Using 1H and 19F NMR Spectroscopy

H-1/F-19 NMR-based screening methods were applied to a human serum albumin-fleroxacin complex. Fleroxacin contains three fluorine atoms in a molecule, which is suitable as a model fluorinated compound for NMR analysis with H-1 and F-19 detection. The F-19{H-1} and H-1{H-1} saturation transfer difference spectra were acquired and the H-1/F-19 spin-lattice relaxation rates were measured with and without any selective irradiation of protein resonance to identify the binding epitopes of fleroxacin. Because several H-1 signals of fleroxacin resonated close to water, its precise signal intensities were unavailable. The F-19 NMR-based screening methods successfully provide complementary information, indicating its importance in the analysis of fluorinated compounds.