Immunoglobulin binding biotinylated

Even greater flexibility was achieved by genetic fusion of streptavidin with protein A [153,154]. Protein A specifically binds the Fc domain of IgG immunoglobulins of almost all mammals without inhibiting the antigen binding activity of the antibody. The streptavidin-protein A fusion construct was used for the assembly of complexes of biotinylated P-galactosidase and different monoclonal antibodies specific for tumour cell receptors. As a result these complexes were efficiently delivered into several cancer cell lines [154]. 

Biotinylated proteins such as immunoglobulins and serum albumins or biotinylated oligonucleotides can bind through affinity interactions streptavidin-functiona-lized Au NPs [156, 157]. 

The gold nanoparticle/polyelectrolyte coated latex particles are then conjugated with biotin molecules through a layer of biotinylated poly(allylamine hydrochloride) that is deposited on the particle surface before biotin binding. Fluorescein isothiocyanate labled anti-biotin immunoglobulin (FITC-anti-biotin IgG)... 

Figure 6.5 Biotin head groups of a surface monolayer bind strongly to the protein streptavidin containing four biotin binding centres. A crystalline protein layer can now be observed by electron microscopy. The other binding centres can now be used to form a third monolayer with biotinylated proteins, e.g. the FAB fragment of F immunoglobulins. ...

If a rabbit primary antibody has been used, then a suitable secondary antibody directed against rabbit immunoglobulins should be selected if a mouse pnmary has been used, select antimouse, and so forth. Secondary antibodies are commonly available with a fluorophore attached for use in immunofluorescence studies. Alternatively, they may be biotinylated, which permits subsequent binding of streptavidin-biotin-horseradish peroxidase complex, or they may have enzymes, such as horseradish peroxidase, attached directly. 

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