title: [Fluorescence spectroscopy study of humen serum albumin quenched by levofloxacin].
abstract: The fluorescence spectroscopy of humen serum albumin (HSA) and the interaction of HSA and the Levofloxacin were studied. When the Levofloxacin was added into HSA solution gradually, an interesting new phenomenon emerged in emission spectrum peak. The intensity of 343.70 nm emission peak of HSA decreased obviously and moved towards long-wavelength, which is atypical quenching phenomenon. It was found that the excitation peak of HSA was positioned at 286.70 nm also. A new emission peak emerged at 503.96 nm, which resulted from the Levofloxacin. The excitation peaks of 503.96 nm fluorescence of Levofloxacin were positioned at 300.16 nm and 336.16 nm. When Levoflaxasin was added into HSA gradually, the 300.16 nm and 336.16 nm excitation peaks moved towards long wavelength. The dissociation constant of Levofloxacin from HSA is about Kd = 3.65 x 10(-5) (mol x L(-1)). The combination constant of Levofloxacin is about Ks = 2.742 x 10(4) (L x mol(-1)). The quenching process of Levofloxacin-HSA is not dynamic quenching, which resulted from the molecular diffusion and collision. It is caused by the static quenching process resulting from the chemical component between molecules. The energy transfer efficiency between Levofloxacin and HSA is E = 0.372. According to these calculation results, the combination position between the binding site of Levofloxacin and the tryptophane of HSA is about R = 1.933 nm.
authors.affiliation: Applied Optics Beijing Area Major Laboratory, Analytic and Testing Center, Beijing Normal University, Beijing 100875, China.
authors.forename: Xiao-bo
authors.initials: XB
authors.lastname: Chen
authors.forename: Dong-guo
authors.initials: DG
authors.lastname: Kang
authors.forename: Song
authors.initials: S
authors.lastname: Li
authors.forename: Cheng-yi
authors.initials: CY
authors.lastname: Zhao
authors.forename: Xiao-shan
authors.initials: XS
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D001665:Binding Sites; D004735:Energy Transfer; D006801:Humans; D007700:Kinetics; D064704:Levofloxacin; D008956:Models, Chemical; D015242:Ofloxacin / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012709:Serum Albumin / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism
chemical_list: D012709:Serum Albumin; D064704:Levofloxacin; D014364:Tryptophan; D015242:Ofloxacin