Binding properties of antibodies

Immunoassay methods exploit the selective recognition and binding properties of antibodies for the recognition and quantitation of antigens or haptens. 

Blake, D.A., Chakrabarti, P., Khosraviani, M., Hatcher, F.M., Westhoff, C.M., Goebel, R, Wylie, D.E., and Blake, R.C., Metal binding properties of a monoclonal antibody directed toward metal-chelate complexes, 7 Biol Chem, 111 (44), 27677-27685, 1996. 

M.-G. Baek, K. Rittenhouse-Olson, and R. Roy, Synthesis and antibody binding properties of glycodendrimers bearing the tumor related T-antigen, Chem. Commun. (2001) 257-258. 

Fig. 11. Schematic representation of the binding properties of anti-idiotype antibodies and antimetatype antibodies. V, hapten a-Id, a-type anti-idiotype antibody /i-Id, /i-type anti-idiotype antibody Met, anti-metatype antibody anti-C-region, antibodies recognizing the constant region of a primary antibody (recognizing isotype or allotype).

The interactions of antibody and antigen are much better understood than are the binding properties of T-cell receptors. However, before focusing on antibodies, we need to look at the humoral and cellular immune systems in more detail to put the fundamental biochemical interactions into their proper context. 

McMahon, M. J., and O Kennedy, R. 2000. Polyreactivity as an acquired artifact, rather than a physiologic property, of antibodies Evidence that monoreactive antibodies may gain the ability to bind to multiple antigens after exposure to low pH. J. Immunol. Methods 247 1-10. 

As part of SW-846, the EPA has validated and approved many immunoassay and colorimetric screening methods for a wide range of contaminants, such as petroleum fuels, pesticides, herbicides, PCBs, and explosives. Immunoassay technology uses the property of antibodies to bind to specific classes of environmental pollutants allowing fast and sensitive semiquantitative or qualitative detection. Colorimetric kits are based on the use of chemical reactions that indicate the presence of target analytes by a change in color. Table 3.9 presents a summary of EPA-approved screening methods and their detection capabilities. 

It was shown I8 that the binding process is the rate-limiting step, with an adsorption rate constant of kd = 4.8 x 104 dm mol s. The calculated mass transfer coefficient for the diffusion into the pores of the support contributes 11% to the overall adsorption process. The value of ka is an order of magnitude lower than that reported in Table 2. The binding properties of the polyclonal immunoadsorbents used in these two studies may differ because of the different methods employed for protein immobilization. Another possible explanation may be an underestimation of the contribution for the diffusion rate-limiting step as the polyclonal anti-HSA antibody was attached to a silica matrix of large pores [18]. 

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