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- Title
Interaction of purified precipitating and non-precipitating (coprecipitating) antibodies with hapten and with haptenated protein. Evidence of an asymmetric antibody molecule.
- Authors
Ronco, J. R.; Sciutto, Edda; Leoni, J.; Margni, R. A.; Binaghi, R. A.
- Abstract
The interaction of monovalent hapten dinitrophenyl ε-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 ix interpreted as due to the existence of two 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 two 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 two molecules of antigen but non-precipitating antibody cannot combine with more than one molecule of antigen. It is concluded that 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.
- Subjects
IMMUNOGLOBULINS; BLOOD plasma; BLOOD proteins; RADIOIMMUNOASSAY; ANIMAL models in research; IMMUNOLOGY
- Publication
Immunology, 1984, Vol 52, Issue 3, p449
- ISSN
0019-2805
- Publication type
Article