Adsorption of Milk Proteins to Phosphatidylglycerol and Phosphatidylcholine Liposomes

Abstract Interactions between various milk proteins and small unilamellar liposomes at pH 6.2 have been followed by measuring the increase in the hydrodynamic radius of the particles using photon correlation spectroscopy. Relatively high salt concentration was required for adsorption of the protein. Observed variations in protein layer thickness between the negatively charged phosphatidylglycerol (PG) liposomes and zwitterionic phosphatidylcholine (PC) liposomes could be explained by reference to the distribution of the charged regions of the proteins and the charge on the surface. Protein layer thicknesses on the negatively charged surface were significantly greater due to charge repulsion between the surface and the negatively charged regions of the proteins.