title: Studies on the interaction of cinnamic acid with bovine serum albumin.
abstract: The interaction between cinnamic acid and bovine serum albumin (BSA) have been studied at three temperatures, 296, 303 and 310 K. Fluorescence quenching spectra in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy was used to investigate the drug-binding mode, the binding constant and the protein structure changes in the presence of cinnamic acid in aqueous solution at pH 7.40. The fluorescence quenching constant K(q), K(sv) and the binding constant K were calculated according to Stern-Volmer equation based on the quenching of the fluorescence of BSA in the presence of cinnamic acid. The thermodynamic parameters, the enthalpy (DeltaH) and the entropy change (DeltaS) were estimated to be -16.457 kJ mol(-1) and 38.028 J mol(-1) K(-1) according to the van't Hoff equation. The displacement experiment shows that cinnamic acid can bind to the subdomain IIA (corresponding to Sudlow's drug binding site I). The distance between the tryptophan residues in BSA and cinnamic acid bound to site I was estimated to be 1.63 nm using Föster's equation on the basis of fluorescence energy transfer. The decreased binding constant in the presence of common ions indicates that common ions have effect on drug-BSA system.
authors.affiliation: College of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin, Guangxi, People's Republic of China.
authors.forename: Hedong
authors.initials: H
authors.lastname: Bian
authors.forename: Hairong
authors.initials: H
authors.lastname: Zhang
authors.forename: Qing
authors.initials: Q
authors.lastname: Yu
authors.forename: Zhenfeng
authors.initials: Z
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Liang
mesh_terms: D002934:Cinnamates / Q000737:chemistry*; D002942:Circular Dichroism; D017433:Protein Structure, Secondary; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D002934:Cinnamates; C029010:cinnamic acid; D012710:Serum Albumin, Bovine