Binding of anti-galactosyl antibodies to galactosylated liposomes.

The binding characteristics of rabbit anti-galactosyl antibodies elicited through galactosylated liposomes were studied. The association constants (13 X 10(5) M-1 and 21 X 10(5) M-1 of Fabmu and Fab fragments with the galactosylated liposomes were determined by measuring the binding of radioiodinated antibodies. The effect of free ligand (methyl-beta-D-galactopyranoside) and the ligand coupled to the liposomal surface (galactosylated liposomes) on the structure of antibodies was investigated using circular dichroism (CD) measurements. Changes were observed in both the secondary and tertiary structure of antibodies upon binding to galactosylated liposomes. In contrast, the free ligand induced alterations only in the near-UV region of the CD spectra, indicating a change in tertiary structure only.