SPECTRAL CHARACTERISTICS OF THE COMPLEXES OF HOECHST33258 WITH BSA

Abstract

Study on the interaction of DNA-specific compound Hoechst 33258 with bovine serum albumin (BSA) has been carried out, using the methods of absorption, differential and fluorescence spectroscopies. On the basis of the absorption and fluorescence spectra of the complexes of this ligand with BSA, in wide interval of the change of r (r=ligand/albumin), the dependence curves of the relative changes of the absorption (A/A0) and fluorescence (F/F0) maxima of the complexes H33258-BSA on the macromolecule concentration, were constructed. The dependence curve of A/A0 monotonously decreases along with protein concentration increasing due to the formation of the complexes. It was revealed that the dependence curve of F/F0 is not linear and is consisted of two regions: at low concentrations of the protein this curve decreases linearly, and passing through the minimum point, at relatively high concentrations of the protein starts linearly increasing. It was also shown that the differential spectra of the complexes H33258-BSA are characterized by hypo- and hyperchromic effects and hypsochromic shift: at low concentrations of the protein a hypochromic effect occurs, at higher concentrations of the protein (beginning from the certain ratios ligand/albumin ~1:1), the differential spectra are hypsochromically shifted with hyperchromic effect. The obtained data find out that Hoechst 33258, being DNA-specific ligand, tightly binds to albumin.