title: Studies of the interaction between paraquat and bovine hemoglobin.
abstract: The interaction between paraquat (PQ) and bovine hemoglobin (BHb) was investigated using fluorescence and UV/vis absorption spectroscopy. The reactivity of the heme centers with superoxide anions formed by PQ was judged on the basis of the decrease of the Soret band. The experimental results showed that the fluorescence quenching of BHb by PQ was a result of the formation of PQ-BHb complex; static quenching was confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K(A) and corresponding thermodynamic parameters were measured at different temperatures. The process of binding PQ molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The effect of PQ on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy.
authors.affiliation: Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, People's Republic of China. wyqing76@126.com
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Wang
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Zhang
authors.forename: Gen-Cheng
authors.initials: GC
authors.lastname: Zhang
authors.forename: Shuang-Xia
authors.initials: SX
authors.lastname: Liu
authors.forename: Qiu-Hua
authors.initials: QH
authors.lastname: Zhou
authors.forename: Zheng-Hao
authors.initials: ZH
authors.lastname: Fei
authors.forename: Zong-Tang
authors.initials: ZT
authors.lastname: Liu
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006418:Heme / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry*; D010269:Paraquat / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013481:Superoxides / Q000737:chemistry*
chemical_list: D006454:Hemoglobins; D013481:Superoxides; D006418:Heme; D010269:Paraquat