Interactions between furcellaran and the globular proteins bovine serum albumin and β-lactoglobulin

The interaction between the algal polysaccharide furcellaran and the globular proteins, bovine serum albumin and beta-lactoglobulin was examined as a function of pH using potentiometric and turbidimetric titration and photon correlation spectroscopy. On decreasing pH, the furcellaran first formed a soluble complex with the globular proteins at a pHc, which showed a maximum in its dependence on ionic strength. On further decrease in pH, the onset of a more substantial aggregation, as indicated by a marked increase in turbidity occurred in the vicinity of the isoelectric point of the protein. Between these pH's the protein/furcellaran complex had a characteristic average size which was larger than the isolated furcellaran chain in solution. Complexation occurred when the protein carried an average net charge of the same sign as the furcellaran. (c) 2006 Elsevier Ltd. All rights reserved.