title: Spectroscopy, calorimetry and molecular simulation studies on the interaction of catalase with copper ion.
abstract: In this research, the binding mechanism of Cu(2+) to bovine liver catalase (BLC) was studied by fluorescence spectroscopy, ultraviolet-visible (UV-vis) absorption spectroscopy, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC) and molecular docking methods. The cellar experiment was firstly carried out to investigate the inhibition effect of catalase. During the fluorescence quenching study, after correcting the inner filter effect (IFE), the fluorescence of BLC was found to be quenched by Cu(2+). The quenching mechanism was determined by fluorescence lifetime measurement, and was confirmed to be the dynamic mode. The secondary structure content of BLC was changed by the addition of Cu(2+), as revealed by UV-vis absorption and CD spectra, which further induces the decrease in BLC activity. Molecular simulation study indicates that Cu(2+) is located between two β-sheets and two random coils of BLC near to the heme group, and interacts with His 74 and Ser 113 residues near a hydrophilic area. The decrease of α-helix and the binding of His 74 are considered to be the major reason for the inhibition of BLC activity caused by Cu(2+). The ITC results indicate that the binding stoichiometry of Cu(2+) to catalase is 11.4. Moreover, the binding of Cu(2+) to BLC destroyed H-bonds, which was confirmed by the CD result.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, 27# Shanda Southroad, Ji'nan 250100, Shandong Province, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Hao
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, 27# Shanda Southroad, Ji'nan 250100, Shandong Province, 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, 27# Shanda Southroad, Ji'nan 250100, Shandong Province, PR China.
authors.forename: Xingchen
authors.initials: X
authors.lastname: Zhao
authors.affiliation: School of Environmental Science and Engineering, Shandong University, China-America CRC for Environment & Health, 27# Shanda Southroad, Ji'nan 250100, Shandong Province, PR China. Electronic address: rutaoliu@sdu.edu.cn.
authors.forename: Rutao
authors.initials: R
authors.lastname: Liu
mesh_terms: D000818:Animals; D002151:Calorimetry; D002374:Catalase / Q000737:chemistry* / Q000378:metabolism*; D002417:Cattle; D003300:Copper / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013057:Spectrum Analysis
chemical_list: D003300:Copper; D002374:Catalase