LIQUID-LIQUID PARTITION CHROMATOGRAPHY AS A METHOD TO EXAMINE SURFACE-PROPERTIES OF ANTIBODIES AND ANTIGEN-ANTIBODY COMPLEXES

We demonstrate liquid-liquid partition chromatography in aqueous two-p hase systems (LLPC) as a simple method for examining the surface prope rties of immunoglobulins and antigen-antibody complexes in solution. L LPC separates molecules with respect to the properties of the exposed surfaces. As an example, the method may be used to detect changes in t he conformation of IgG following chemical modification like acylation or iodination. We have studied the partitioning of antibodies and anti gen-antibody complexes, modelled by rabbit antibodies against three hu man serum proteins, in aqueous polyethylene glycol/dextran two-phase s ystems at pH 7. Analysis of both polyclonal and monoclonal antibodies against various antigens suggested that the partition properties of im munoglobulins are related mainly to their antigen specificity and not to subclass-specific structures. Furthermore, experiments indicated th at changes in the surface properties of antigen and/or antibody follow ing complexation may be detected. Thus, LLPC may prove to be a new way of studying the relation between antibody structure and function in s olution.