title: Comparison of the interaction between lactoferrin and isomeric drugs.
abstract: The binding properties of pentacyclic triterpenoid isomeric drugs, i.e. ursolic acid (UA) and oleanolic acid (OA), to bovine lactoferrin (BLF) have been studied by molecule modeling, fluorescence spectroscopy, UV-visible absorbance spectroscopy and infrared spectroscopy (IR). Molecular docking, performed to reveal the possible binding mode or mechanism, suggested that hydrophobic interaction and hydrogen bonding play important roles to stabilize the complex. The results of spectroscopic measurements showed that the two isomeric drugs both strongly quenched the intrinsic fluorescence of BLF through a static quenching procedure although some differences between UA and OA binding strength and non-radiation energy transfer occurred within the molecules. The number of binding sites was 3.44 and 3.10 for UA and OA, respectively, and the efficiency of Förster energy transfer provided a distance of 0.77 and 1.21nm for UA and OA, respectively. The conformation transformation of BLF affected by the drugs conformed to the "all-or-none" pattern. In addition, the changes of the ratios of α-helices, β-sheets and β-turns of BLF during the process of the interaction were obtained. The results of the experiments in combination with the calculations showed that there are two modes of pentacyclic triterpenoid binding to BLF instead of one binding mode only governed by the principle of the lowest bonding energy.
authors: Department of Chemistry, Zhejiang Agricultural & Forestry University, Lin'an 311300, Zhejiang, China. Electronic address: tdky@hotmail.com.
authors: Ming
authors: M
authors: Guo
authors: Department of Chemistry, Zhejiang Agricultural & Forestry University, Lin'an 311300, Zhejiang, China.
authors: Xiaowang
authors: X
authors: Lu
authors: Department of Chemistry, Zhejiang Agricultural & Forestry University, Lin'an 311300, Zhejiang, China.
authors: Yan
authors: Y
authors: Wang
authors: Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82 Kalmar, Sweden. Electronic address: peter.brodelius@lnu.se.
authors: Peter E
authors: PE
authors: Brodelius
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004735:Energy Transfer; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007536:Isomerism; D007781:Lactoferrin / Q000737:chemistry / Q000378:metabolism*; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009828:Oleanolic Acid / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014315:Triterpenes / Q000737:chemistry* / Q000378:metabolism*; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism; D000097245:Ursolic Acid
chemical_list: D007781:Lactoferrin; D008670:Metals; D009828:Oleanolic Acid; D014315:Triterpenes; D014364:Tryptophan; D000097245:Ursolic Acid
keywords: Bovine lactoferrin; Interaction; Oleanolic acid; Ursolic acid