title: Fluorescence decay time distribution analysis reveals two types of binding sites for 1,8-anilinonaphthalene sulfonate in native human oxyhemoglobin.
abstract: Binding of 1,8-anilinonaphthalene sulfonate (1,8-ANS) with native human oxyhemoglobin (Hb) in 50 mM potassium phosphate buffer (pH 7.4) was studied by steady-state fluorescence spectroscopy and by laser spectrofluorimetry with subnanosecond time resolution. The distribution of fluorescence decay times and parameters of two- and three-exponential deconvolution of the fluorescence kinetics of 1,8-ANS in Hb solution demonstrate that the emission at wavelengths lambdaem of 455-600 nm is not single-exponential and has components with mean decay times < 0.5, 3.1-5.5, and 12.4-15.1 nsec with the amplitudes depending on the emission wavelength. Analysis of time-resolved fluorescence spectra shows that the shortest-lived component should be assigned to 1,8-ANS molecules in the aqueous medium, whereas the two longer-lived components are assigned to two types of binding sites for 1,8-ANS in the Hb molecule characterized by different polarity and accessibility to water molecules.
authors.affiliation: Sakharov International Ecological University, Minsk, 220009, Belarus.
authors.forename: D A
authors.initials: DA
authors.lastname: Parul
authors.forename: S B
authors.initials: SB
authors.lastname: Bokut
authors.forename: P A
authors.initials: PA
authors.lastname: Kisselev
authors.forename: A A
authors.initials: AA
authors.lastname: Milyutin
authors.forename: E P
authors.initials: EP
authors.lastname: Petrov
authors.forename: N A
authors.initials: NA
authors.lastname: Nemkovich
authors.forename: A N
authors.initials: AN
authors.lastname: Sobchuk
authors.forename: B M
authors.initials: BM
authors.lastname: Dzhagarov
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites / Q000502:physiology; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D010108:Oxyhemoglobins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D010108:Oxyhemoglobins; C027132:1-anilino-8-naphthalenesulfonate