Investigation of interaction of anionic polyelectrolytes with bovine serum albumine by fluorescence metods

The process of forming water soluble and insoluble complexes from polyelectrolytes andproteins, the structure of the forming polycomplex particles and their morphology, and thepresence of interphasal transformation within these systems, have been examined by differentphyscochemical methods.The information about fluorescence, phosphorescence, quantity specification in lowconcentrations, bioluminescence, protein quantity specification, and analysis of threedimensional structure of proteins, etc. are analyzed by fluorescence spectrometer method.Despite the fact that fluorescence method can give spectacular information concerning theexamination of interactions between proteins and polyelectrolytes, examination of theinteractions possible between polyelectrolyte-protein mixtures using the fluorescence methodhave been successfully realized on a few number of systems.In this study, the interaction of Bovine Serum Albumin (BSA) with anionic polyacrylic acid(PAA) has been examined and the formation of interpolymer-protein complex based on thevariation of the fluorescence aspects of the tryptophan amino acid present in protein moleculehas been researched. It has been determined that, water soluble and insoluble polymer-proteincomplexes have been formed depending on the ratio of the components and the pH value ofthe environment. As the phase transformation has been occuring and meanwhile importantchanges have taken place in three dimensional structures of stable polycomplex particlesaccording to the conditions. Aggregation of intrapolymer complexes has been founddepending on the ratio and pH value. λmax and Imax values of tryptophan in the structure ofprotein molecule change according to the ratio and pH. It is still a subject of dispute whetherthese changes arise from the structure of protein or from the formed polycomplex.Since the fluorescence method is applied to the water soluble PAA-protein mixtures, thewater solubility of the system has been researched primarily by turbidimetric methoddepending on the polymer/protein ratio and the pH value of the mixture, and insolublesystems have been determined. As the pH decreases, completely water soluble polymer-protein mixture becomes insoluble in neutral pH environment as in pH values close toisoelectric point and in lower pH values.These systems have been researched in detail using fluorescence method and new informationwhich is not present in the literature has been gathered. For the time being, there are nodetailed information about the ratio of compounds (polymer and protein) in the structure ofpolycomplex, the chemical bonds within the polycomplex and the nature of their interaction,the three dimensional structures of the whole polycomplex particles and the protein moleculethey embody.Key words: polyelectrolyte, poliacrylic acid, bovine serum albumin, fluorescence.