INTERACTION OF PURIFIED PRECIPITATING AND NON-PRECIPITATING (COPRECIPITATING) ANTIBODIES WITH HAPTEN AND WITH HAPTENATED PROTEIN - EVIDENCE OF AN ASYMMETRIC ANTIBODY MOLECULE

Google Scholar
  • 1 January 1984
    • journal article
    • research article
    • Vol. 52  (3) , 449-456
Abstract
The interaction of monovalent hapten dinitrophenyl .epsilon.-amino caproic acid (DNP-EACA) with purified IgG1 sheep anti-DNP precipitating and non-precipitating antibodies and their F(ab'')2, F(ab'') and Fab fragments, was studied by fluorescence quenching and by a radioimmunoassay. The Scatchard plots of whole non-precipitating antibody and its F(ab'')2 fragment showed a bi-modal curve that could be interpreted as due to the existence of 2 populations of sites with very different affinity for the ligand, each population representing 50% of the total number of sites. The F(ab) fragments of the non-precipitating antibody could be fractionated by immunoadsorption into 2 populations of high and low affinity whose association constants differed by more than 2 logs. The study of the interaction of whole antibodies with DNP-bovine serum albumin (BSA) demonstrated that each molecule of precipitating antibody can combine with 2 molecules of antigen but non-precipitating antibody cannot combine with more than 1 molecule of antigen. The molecule of non-precipitating antibody is asymmetric and has a site of high affinity and another of low affinity. As a consequence of this structure the non-precipitating antibody behaves functionally as univalent and is unable to form precipitates with the multivalent antigen and to activate effector mechanisms.