title: Cobinding of bilirubin and laurate to human serum albumin: spectroscopic characterization of stoichiometric complexes.
abstract: Light absorption and CD spectra of bound bilirubin and albumin fluorescence spectra have been recorded from mixtures containing albumin, A, bilirubin, B, and laurate, L, in Tris-NaCl buffer at pH 8.2, 25 degrees C. Concentrations of the corresponding stoichiometric complexes, ABiLj, for i = 0/3 and j = 0/3, have been calculated from previously determined stoichiometric cobinding constants (H. Sato et al. (1988) Arch. Biochem. Biophys. 260, 811-821). Spectral data of the complexes have finally been found by iterative computer fitting using the principle of several acceptable solutions (R. Brodersen et al. (1987) Eur. J. Biochem. 169, 487-495). The results were utilized at the microscopic level to investigate ligand-induced conformational changes. When laurate was bound to AB, a decrease of the distance between Trp-214 and the bound bilirubin occurred, as measured according to Förster's principle. The distances were 21.9 +/- 0.3 A in AB, 19.7 +/- 0.3 A in ABL, and 17.9 +/- 0.2 A in ABL2.
authors.affiliation: Institute of Medical Biochemistry, University of Aarhus, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Honoré
authors.forename: H
authors.initials: H
authors.lastname: Sato
authors.forename: R
authors.initials: R
authors.lastname: Brodersen
mesh_terms: D001663:Bilirubin / Q000378:metabolism*; D002942:Circular Dichroism; D006801:Humans; D066298:In Vitro Techniques; D007850:Lauric Acids / Q000378:metabolism*; D046911:Macromolecular Substances; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis; D014364:Tryptophan
chemical_list: D007850:Lauric Acids; D046911:Macromolecular Substances; D012709:Serum Albumin; C030358:lauric acid; D014364:Tryptophan; D001663:Bilirubin