title: [Spectroscopic study on interaction between cistanoside F and bovine serum albumin].
abstract: OBJECTIVE
  To study the conjugation reaction characteristics of caffeic acid micromolecule cistanoside F and bovine serum albumin.
  
  
  METHODS
  The interaction between bovine serum albumin (BSA) and cistanoside F that was separated from Callicarpa plant for the first time and abbreviated CF was detected by fluorescence (FS), UV-vis absorbance and circular dichroism (CD) under simulative physiological conditions.
  
  
  RESULTS
  CF-BSA's static apparent binding constant (K(a)), number of binding sites (n), efficiency of energy transfer (E), spatial distance (r), thermodynamic parameters deltaG, deltaH and deltaS and changes in alpha-helical structure content in BSA before and after CF's effect were calculated to define the binding site of CF in BSA and analyze the impact of several common metal ions on the interaction of CF and BSA.
  
  
  CONCLUSIONS
  Ground state compounds formed by CF and BSA could cause intrinsic fluorescence quenching. Their binding constant K(a) of cistanoside F with BSA was 4.36 x 10(4) L x mol at 25 degrees C, the number of binding site n was 1, and the spatial distance r was 3.09 nm. The results indicated that the hydrogen bond played a major role in cistanoside F-BSA association. The displacement experiments confirmed that cistanoside F can bind to site I of BSA. In addition, the binding constant of cistanoside F with BSA was enhanced after the addition of some common metal ions Mg2+, Fe3+, Cu2+ and Zn2+. The intrinsic fluorescence of BSA was quenched by cistanoside F via forming cistanoside F-BSA complex and non-radiation energy transfer. CD spectra showed that the binding of cistanoside F with BSA induced conformational changes in BSA.
authors.affiliation: School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
authors.forename: Aizhi
authors.initials: A
authors.lastname: Wu
authors.forename: Chaozhan
authors.initials: C
authors.lastname: Lin
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Zhao
authors.forename: Jialin
authors.initials: J
authors.lastname: Zhuo
authors.forename: Chenchen
authors.initials: C
authors.lastname: Zhu
mesh_terms: D000818:Animals; D002109:Caffeic Acids / Q000737:chemistry; D002396:Catechols / Q000737:chemistry*; D002417:Cattle; D002942:Circular Dichroism; D006027:Glycosides / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D002109:Caffeic Acids; D002396:Catechols; D006027:Glycosides; C574495:cistanoside F; D012710:Serum Albumin, Bovine