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Assessment on the binding characteristics of residual marbofloxacin in animal‐derived food to bovine/human serum albumin by spectroscopy and molecular modelling
Author(s) -
Li Xu,
Yuan Yue,
Zhao Rui,
Shao Di,
Bi Shuyun
Publication year - 2021
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.4022
Subject(s) - chemistry , bovine serum albumin , circular dichroism , quenching (fluorescence) , hydrogen bond , human serum albumin , binding constant , fluorescence spectroscopy , fluorescence , binding site , van der waals force , analytical chemistry (journal) , chromatography , crystallography , molecule , biochemistry , organic chemistry , physics , quantum mechanics
To assess the toxicity of residual marbofloxacin from animal‐derived food, the interaction characteristics of marbofloxacin to bovine/human serum albumins (BSA/HSA) were explored using spectroscopic methods combined with molecular modelling. According to fluorescence spectra and time‐resolved fluorescence spectra measurements, quenching of BSA/HSA fluorescence induced by marbofloxacin was characterized as static quenching. A 1:1 ground‐state complex of marbofloxacin to BSA/HSA was formed with binding constant ( K a ) 1.66 × 10 4 /9.74 × 10 3 M −1 at 291 K. The location of marbofloxacin binding at site I within BSA/HSA was clarified by site marker competitive experiments. Molecular modelling demonstrated that the binding region for marbofloxacin to BSA and HSA were at site I with the lowest binding free energies of −22.86 and −21.60 kJ mol −1 , respectively. Hydrogen bonds and van der Waals forces were dominantly involved in the spontaneous binding. Nonradiation energy transferred from BSA and HSA to marbofloxacin, due to the close distance ( r 0 ) between marbofloxacin and Trp residues of BSA (4.28 nm) and HSA (3.34 nm). As explained by circular dichroism (CD) spectra, an increased BSA/HSA α‐ helix structure was observed after binding to marbofloxacin. Ultraviolet–visible (UV–vis) and Fourier transform infrared (FT‐IR) spectra suggested that conformation of the two proteins was altered by marbofloxacin.