title: Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies.
abstract: Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, 27# Shanda South Road, Jinan 250100, PR China.
authors.forename: Mingyang
authors.initials: M
authors.lastname: Jing
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, 27# Shanda South Road, Jinan 250100, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, Shandong Province, 27# Shanda South Road, Jinan 250100, PR China. Electronic address: rutaoliu@sdu.edu.cn.
authors.forename: Rutao
authors.initials: R
authors.lastname: Liu
mesh_terms: D000818:Animals; D001665:Binding Sites; D002151:Calorimetry; D002645:Chickens; D002942:Circular Dichroism; D003300:Copper / Q000378:metabolism*; D062105:Molecular Docking Simulation; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D003300:Copper; D009113:Muramidase
keywords: Copper; Isothermal titration calorimetry; Lysozyme; Molecular docking; Multi-spectroscopic measurements