title: Multivariate analysis of the association of bromocresol purple anion with bovine serum albumin.
abstract: The interaction of bromocresol purple (BCP) anions with bovine serum albumin (BSA) was investigated by principal factor analysis method, and reaction model, the number of molecular species and spectra of each component present in the reaction mixture were determined. The number of molecular species concerning the absorption intensity was three, including free BCP anion. Most part of the spectral change could be explained by the monomer binding of bromocresol purple anion (D) to serum albumin (P), a simple one step equilibrium, P + D = PD. A second type of association of BCP anions with serum albumin was also present, though in a small amount. Of six models tested which consisted of three or four molecular species, the sequential two step reaction model, P = PD = PD2, was the best model to explain the spectral data, and an existence of BCP anions as a dimer on the serum albumin was demonstrated. The dissociation constants were estimated at K1 = 1.6 x 10(-6) M for the first step and K2 = 1.2 x 10(-5) M for the second step.
authors.affiliation: Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan. nak@biows.kaws.coge.tohoku.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamaru
authors.forename: C
authors.initials: C
authors.lastname: Sato
mesh_terms: D001962:Bromcresol Purple / Q000378:metabolism*; D003198:Computer Simulation; D019281:Dimerization; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D001962:Bromcresol Purple; D012710:Serum Albumin, Bovine