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 β-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.