Antigen-antibody complex, analysis

In this context, Greene and coworkers [159, 160] have reported the first low-molecular-mass immunoglobulin mimetic 207, Scheme 62, developed on the basis of an X-ray structure analysis of the antigen-antibody complex. Compound 207 is resistant toward proteases and imitates the binding and functional properties of the native antibody. 

One of the first applications of magnetic separation in bioanalysis involves immunoassays (for a review, see Pour Carzaneh et al. (111). Here one specie of the immune couple is immobilized onto the magnetic particle and magnetic separation is performed after formation of an antigen-antibody complex. After proper washing, dissociation of the complex was performed before reading the outcome from the analysis as the amount of bound and then liberated material. 

K max when the fluorescence signal is saturated at /— < , and a = / bg- / m x where / bg is the background fluorescence signal at / = 0. This result is identical to the output signal of bio-molecules interaction analysis of complex in the real time by using SPR biosensor (265). From Eq. (41), the linear relationship... 

Radioimmunoassay (RIA) is a technique based on the formation of antigen-antibody complex. This technique essentially involves the application of isotope dilution analysis. An antigen is typically a protein of molecular weight greater than 10,000 that stimulates the production of antibody in an animal body. The antigen subsequently binds with the antibody. 

Both universal staining procedures and specific detection techniques can be performed after (electro) transfer or (electro)blotting of proteins (also called Western blotting) from the gel matrix (which sometimes hinders protein analysis) to a nitrocellulose or polyvinylidenedifluoride membrane, to which they are bound and immobilized. On the membrane, protein molecules are faster and better accessible for the interactions with the applied specific antibodies. The antigen-antibody complexes are visualized by a second antibody (against the first antibody) with an attached enzyme label, which catalyzes the color reaction in the place of the protein zone. 

Fig. 6 Evaluation of phosvitin binding to monoclonal anti-phosphoserine antibody by ACE using mobility-shift analysis and UV detection. Peaks M, internal peptide marker mAb, free monoclonal anti-phosphoserine antibody mAb-hpAg complex, monoclonal anti-phosphoserine antibody complexed with homopolyvalent phosvitin antigen. The buffer contained phosvitin within a concentration from 0 to 60 /xM. (Reprinted with permission from Ref. 27. Copyright 1997 Academic Press.)... 

Any radioimmunoassay analysis relies upon the efficiency of the separation of the unbound (free) antigen or hapten from that bound to antibody. When using immunoassay to estimate low molecular weight compounds such as steroids, the problem is perhaps somewhat simpler than in protein immunoassay. Because of the large difference in molecular weight between steroid haptens and their appropriate antibodies, relatively simple methods of separation, such as dialysis, can be used. Although nonspecific precipitation of the antibody-bound steroid by ammonium sulfate and polyethylene glycoH are widely used, the utilization of second-anti-body immunoprecipitation of the steroid-antibody complex is not com-... 

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