title: Probing the binding of two fluoroquinolones to lysozyme: a combined spectroscopic and docking study.
abstract: Ciprofloxacin (CPFX) and enrofloxacin (ENFX) are two of the most widely used fluoroquinolones (FQs) in human and veterinary medicines. Their occurrence in the environment has received much attention because of the potential adverse effects on humans and ecosystem functions. In this paper, we investigated the interaction mechanism between the two FQs and lysozyme by the spectroscopic and molecular docking methods. As shown by the fluorescence spectroscopy, additions of CPFX or ENFX effectively quenched the intrinsic fluorescence of lysozyme, which was attributed to the formation of a moderately strong complex. The enthalpy change (ΔH) and entropy change (ΔS) indicated that van der Waals forces and hydrogen bonds were the dominant intermolecular forces in the binding of two FQs to lysozyme. Furthermore, data obtained by UV-vis absorption, synchronous fluorescence and circular dichroism (CD) suggested that both CPFX and ENFX could lead to the conformational and some microenvironmental changes of lysozyme. Finally, the molecular docking illustrated that the two FQs had specific interactions with the residues of Trp62 and Trp63.
authors.affiliation: Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, Jinan 250100, PR China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Qin
authors.forename: Baoling
authors.initials: B
authors.lastname: Su
authors.forename: Rutao
authors.initials: R
authors.lastname: Liu
mesh_terms: D002939:Ciprofloxacin / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism / Q000379:methods; D003198:Computer Simulation; D000077422:Enrofloxacin; D024841:Fluoroquinolones / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D024841:Fluoroquinolones; D000077422:Enrofloxacin; D002939:Ciprofloxacin; D009113:Muramidase