in ELISA, why the assay need secondary antibody labeled, why no just label the primary antibody?
in ELISA, why the assay need secondary antibody labeled, why no just label the primary antibody?
Last Updated on Friday, 2 July 2010 10:09 Written by Administrator Friday, 2 July 2010 10:09
Question by teck kim: in ELISA, why the assay need secondary antibody labeled, why no just label the primary antibody?
Best answer:
Answer by Isopropyl_Dog
antibodies have two sides: a constant region and a variable region. So the primary antibody has a variable region that specifically binds to the antigen of interest… this primary antibody can be made naturally by the immune system of an organism. If a person is exposed to antigen X, the natural process in his body will create anti-X antibodies. So then we could take a sample of his blood and collect the anti-X antibodies (with affinity chromatography this is easy), purify them and use them in an ELISA to detect antigen X. Unfortunately the natural process does not label the antibodies… thats why we need secondary antibodies.
The secondary antibody specifically binds to the constant region of the primary antibody (all the primary antibodies will have similar constant regions) and has a detectable probe. So you can use the same secondary antibody with lots of different primary antibodies.
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