title: Binding properties of herbicide chlorpropham to DNA: spectroscopic, chemometrics and modeling investigations.
abstract: The binding properties of chlorpropham (CIPC) to calf thymus DNA (ctDNA) were investigated in vitro by UV-vis absorption, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy coupled with molecular modeling method. The results obtained from UV-vis absorption, fluorescence and CD spectroscopic methods as well as DNA viscosity and melting measurements indicated that the binding of CIPC to ctDNA was an intercalative mode. The FT-IR analysis and molecular modeling showed that CIPC mainly bound to guanine base of ctDNA. The association constant of the ctDNA-CIPC complex was determined to be in the order of 10(4) L mol(-1) by fluorescence titration. The calculated enthalpy change and entropy change suggested that hydrophobic forces and hydrogen bonds played prominent roles in the binding process. Furthermore, multivariate curve resolution-alternating least squares (MCR-ALS) approach was used to analyze the combined UV-vis absorption data matrix from the CIPC-ctDNA reaction system. The concentration profiles of the reaction components (CIPC, ctDNA and CIPC-ctDNA complex) and their pure spectra were successfully obtained to monitor the process of CIPC interaction with ctDNA. This study may contribute to the understanding of the CIPC-ctDNA interaction mechanism and toxicological effect of CIPC at the molecular level.
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, Jiangxi, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, Jiangxi, China. Electronic address: gwzhang@ncu.edu.cn.
authors.forename: Guowen
authors.initials: G
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, Jiangxi, China.
authors.forename: Mo
authors.initials: M
authors.lastname: Tao
mesh_terms: D000818:Animals; D002417:Cattle; D002748:Chlorpropham / Q000737:chemistry*; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D019277:Entropy; D006540:Herbicides / Q000737:chemistry*; D008958:Models, Molecular; D044367:Phase Transition; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014783:Viscosity
chemical_list: D006540:Herbicides; D002748:Chlorpropham; D004247:DNA; C427203:calf thymus DNA
keywords: Binding properties; Calf thymus DNA; Chlorpropham; Intercalation; Multivariate curve resolution-alternating leas squares