Bonds antigen-antibody

Affinity chromatography (12) has become an important tool in the isolation of purified fractions of such substances as enzymes. Advantage is taken of specific interactions such as antigen-antibody interactions. One substance of the pair (e.g. antigen) is bonded to a support. When a mixture is passed through the column, the specific interaction retains the corresponding antibody relative to other substances. A change of mobile phase conditions then elutes the pure antibody. This method has a real potential for analysis of specific proteins in body fluids. 

Antibody avidity is commonly applied to antigen-antibody interaction, where multiple, weak, noncovalent bonds form between antigen and antibody. Avidity is distinct from affinity, which is a term used to describe the strength of a single bond. As such, avidity is the combined synergistic strength of bond affinities rather than the sum of bonds. 

Fields, B.A., F.A. Goldbaum, W. Dall Acqua, E.L. Malchiodi, A. Cauerhff, F.P. Schwarz, X. Ysem, R.J. Poljak, and R.A. Mariuzza. 1996. Hydrogen bonding and solvent structure in an antigen-antibody interface. Crystal structures and thermodynamic characterization of three Fv mutants complexed with lysozyme. Biochemistry 35 15494-15503. 

Additional reports include the covalent bonding of antibodies to functionalized sol-gel films55, the entrapment of polyclonal fluorescein56, the development of a sol-gel enzyme-linked immunosorbent assay (ELISA) test for antigenic parasitic protozoa57 and an immunoassay for the detection of 1-nitropyrene58. 

More recently, the use of fluorine to probe hydrogen-bonding interactions has been demonstrated in the study of antigen-antibody interactions. A series of deoxyfluoroglv-cosides were used as probes to define binding sites of antisachharide immunoglobulins141. 

The reversible dissociation of antigen-antibody bonds by nonaqueous solvents such as dioxane may prove of considerable practical use in procedures for the isolation and purification of specific antibodies (cf. Singer et al., 1960). 

The adsorption process, unlike antigen-antibody interactions, is nonspecific. Thus, during the incubation of the immobilized antigen or antibody with enzyme-labeled antigen or antibody, the latter binds specifically to the immobilized immune reactant, but may also be adsorbed directly onto the solid phase. This nonspecific adsorption of enzyme activity can be minimized by inclusion of a nonionic detergent such as Triton X-lOO or Tween 20. These do not interfere with the antigen-antibody reaction but prevent formation of new hydrophobic interactions between added proteins and the solid phase without disrupting to any appreciable extent the hydrophobic bonds already formed between the previously adsorbed protein and the plastic surface. 

Xia Z, Goldsmith HL, and van de Ven TG. Flow-induced detachment of red Mood cells adhering to surfaces by lecific antigen-antibody bonds. Biophys J 1994 66 1222-1230. 

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