title: Assessment of the europium(III) binding sites on albumin using fluorescence spectroscopy.
abstract: Intrinsic fluorescence quenching of bovine serum albumin (BSA) and europium(III) luminescence in BSA complexes were investigated. The number of BSA binding sites (n) and equilibrium constant (Keq) values were determined from both measurements provided qualitatively different results. While the modified Stern-Volmer relation for BSA fluorescence quenching gave n = 1 at pH 4.5 and pH 6, two sets of binding sites were determined from Eu(3+) luminescence with n1 = 2, n2 = 4 at pH 6 and n1 = 1, n2 = 2 at pH 4.5. The model explaining the discrepancy between the results obtained by these fluorescent approaches was suggested, and the limitations in application of the "log-log" Stern-Volmer plots in analysis of binding processes were discussed.
authors.affiliation: International Laser Center and ‡Department of Physics, M.V. Lomonosov Moscow State University , Moscow 119991, Russia.
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Tikhonova
authors.forename: Evgeny A
authors.initials: EA
authors.lastname: Shirshin
authors.forename: Gleb S
authors.initials: GS
authors.lastname: Budylin
authors.forename: Victor V
authors.initials: VV
authors.lastname: Fadeev
authors.forename: Galina P
authors.initials: GP
authors.lastname: Petrova
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D005063:Europium / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D012710:Serum Albumin, Bovine; D005063:Europium