Interaction of β-lactoglobuline and strong polyelectrolytes: a computational study

Abstract

β-lactoglobuline is the main protein on serum lactum, it has an important nutritional value. The principal objective is the purification of the β-lactoglobulina through simple, fast and economic methods for their industrial application. In the presence of a polyelectrolyte (PE) it can be obtained complex with the BLG. This complex formed in specific conditions are insoluble and easily separated. In this work, we study at molecular level the interaction between a protein molecule of BLG and strong polyelectrolytes chain. The methodology used consist in a coarse grain model with a minimum number of parameters that allow us to represent the physicochemical essence of the process and simulations are performed with the Monte Carlo method. The adsorption of the polyelectrolyte on the protein surface was molecularly quantified with a structural criterion. It was quantified the amount of ionic pairs, a charged monomer with an oppositely charged residue of the protein. Results showed that the interaction protein – polyanion was favored at pH below the isoelectric point (pI) of the protein. On the other hand, it was found that the interaction proteinpolycation started on the wrong side of the pI of the protein. It was found that this was due to the charge regulation mechanism of the protein, and mainly the glutamic and aspartic groups.