Water-insoluble complexes of protein with polyacrilic acid

In the studies before, structure, morphology and the formation process of water-soluble andinsoluble complexes of polyelectrolytes with proteins and existence of phase transition inthese systems were investigated.In this study, the interaction of PAA with BSA was investigated with turbidimetric titrationmethod. It?s known that turbidimetric titration method is one of the most suitable methods todetect the formation of insoluble interpolymer complexes and transition to soluble state. Inthis study, interactions were investigated at different BSA/PAA ratios and system pH?s due tothe fact that both PAA and BSA provide different charges depending on pH and componentsof the system effect the interaction mechanism. It?s observed that, the complexes transforminto water-insoluble at the approximate pH values to pI (isoelectric point) and below the pI,while the mixture of polymer-protein is completely water-soluble at neutral pH.For the first time, by us, it?s observed that, at a constant BSA/PAA ratio, titration curvesobtained by increasing or decreasing pH were not fit into each other and detected that thesetwo curves display hysteresis.Key words: polyelectrolyte, poliacrylic acid, bovine serum albumin, turbidimetry