Antigens interactions

By similar logic, protein affinity Hbraries have been constmcted to identify protein—protein combining sites, as in antibody—antigen interaction (19) and recombinant Hbraries have been made which produce a repertoire of antibodies in E. coli (20). In another case, a potential DNA-based therapeutic strategy has been studied (21). DNAs from a partially randomized Hbrary were selected to bind thrombin in vitro. Oligonucleotides, termed aptamers that bound thrombin shared a conserved sequence 14—17 nucleotides long. 

The affinity method may be biospecific, for example as an antibody-antigen interaction, or chemical as in the chelation of boronate by ci5-diols, or of unknown origin as in the binding of certain dyes to albumin and other proteins. 

Wilson, I.A., 5tanfield, R.L. Antibody-antigen interactions new structures and new conformational changes. 

FIG. 4.1. Schematic representation of two antibodies reacting with a continuous and a discontinuous epitope of a protein antigen interacting residues are indicated in black. If the individual loops of a discontinuous epitope are able to bind to the antibody paratope on their own, they may be given the status of continuous epitope. The inset shows the three loops of an antibody VH chain which form part of the paratope... 

Huebner J. Antibody-antigen interactions and measurements of immunologic reactions. In Immunology, Infection, and Immunity, 1st edition, ed. GB Pier, JB Lyczak, and LM Wetzler, pp. 209-210. Washington, DC American Society for Microbiology, 2004. 

There is a continuing demand for fast and simple analytical methods for the determination of many clinical, biochemical and environmental analytes. In this respect, immunoassays and immunosensors that rely on antibody-antigen interactions provide a promising means of analysis owing to their specificity and sensitivity. High specificity... 

R.M.T. de Wildt, C.R. Mundy, B.D. Gorick, and I.M. Tomlinson, Antibody arrays for high-throughput screening of antibody-antigen interactions. Nature Biotech. 18, 989—994 (2000). 

Immunoassays employ monoclonal or polyclonal antibody preparations (Chapter 13) to detect and quantify the product (Box 7.1). The specificity of antibody-antigen interaction ensures good assay precision. The use of conjugated radiolabels (RIA) or enzymes (EIA) to allow detection of antigen-antibody binding renders such assays very sensitive. Furthermore, when compared with... 

Tsumoto, K., Y. Ueda, K. Maenaka, K. Watanabe, K. Ogasahara, K. Yutani, and I. Kumagai. 1994. Contribution to antibody-antigen interaction of structurally perturbed antigenic residues upon antibody binding. J Biol Chem 269 28777-28782. 

By allowing multiple secondary antibodies, each with several enzyme molecules attached to bind to the primary antibody, the amount of enzyme at the site of the primary antihody-antigen interaction can be increased along with the resultant signal. This makes the reaction easier to observe but also increases the visibility of weak reactions, thereby increasing the overall sensitivity of the method. In addition, the background is reduced and the primary antibodies can be diluted even further with little loss in detectability. This produces a technique that is not only more cost-effective, but also is more specific resulting from a decrease in the concentration of any nonspecific antibodies in the primary antisera. 

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