CHANGES IN CONFORMATION OF HUMAN SERUM-ALBUMIN (HSA) AND GAMMA-GLOBULINS (GAMMA-G) UPON ADSORPTION TO POLYSTYRENE AND POLY(STYRENE/ACROLEIN) LATEXES - STUDIES BY FLUORESCENCE SPECTROSCOPY

Changes of human serum albumin (HSA) and gamma globulins (gamma G), labelled with 1-pyrene-carboxaldehyde (PCA) and/or with 1,3-bis(1-pyrene)-propane (BPP), resulting from interactions with polystyrene (PS) and poly(styrene/acrolein) (PSA) latexes, were investigated by fluorescence spectroscopy. The proteins in solution readily exchanged with the adsorbed proteins. The fluorescence spectra of the PCA label and BPP probe, incorporated into the protein macromolecules, indicate that the protein macromolecules undergo significant conformational changes on contact with the surface of the latex particles, and that these changes are not reversible. The internal fluidity for desorbed protein macromolecules is lower than before the interaction with the latex particles. Moreover, due to the conformational changes the PCA labels, formerly present in the hydrophilic and hydrophobic protein regions, became located predominantly in the latter. The differences in the emission spectra for the labelled proteins before attachment to the latex particles and after desorption were used to study the kinetics of the protein conformational changes. The dependence of the overall rate constants for protein conformational rearrangements on the latex concentration was investigated.