sturge_weber
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an antiserum containg IGg against the large protein antigen keyhole limpet hemocyanin {klh} is treated with pepsin. after refrigeration overnight the resulting suparnatent is mixed with klh. the final mixture will
a. agglutinate klh
b. precipitate klh
c.bind complement
d. bind phagocytic cells
e. lose cross linking ability
well the q is easy, but how do we know whether klh is soluble or insoluble, and hence will precipitate or agglutinate respectively?????
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| msyamp
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i think if it is an protein antigen - antibody it is agglutination this is also for rbc.
but i dont know correctly how to diff. but now the answer is agglutination right?
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| sturge_weber
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no the ans is precipitate ...ie choice e...
if anybody knows ........
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| sturge_weber
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anyone
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| ssrpk
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well the questin is simple but the choices are confusing me!
here's how i look at it!
- antibody has 2 FAB and 1 Fc fragments.
- two enzymes (Papain and Pepsin) digest them producing differnet type of fragments.
- Pepsin produces several fragments of Fc while the 2 FAB remains interlinked, thus remain bivalent.
- Papain on the other hand disintegrates the whole and even separates the the two FAB, thus they become monovalent.
- as bivalent has two binding sites thus , it can agglutinate or precipitate the antigens that are attached to them.
Whtz the differnec b/w agglutination and precipitation in this context ????
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| skyhigh
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it think crosslinking ablility is lost, and there is no agglutination because the SUPERNATANT to which the antigen(klh) is added does not have the bivalent FAB fragments..
This is because the light chains which make up the Fc fragments remain the supernatant and the FAB fragments which are made up of the light and the heavy chains sink to the bottom.
I think if the question asked what would happen if the antigen(klh) is added to the bottom layer of the refrigerated material (which is not the SUPERNATANT), then agglutination would be the answer.
I don't know if I am right, but this is what I am thinking.
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| elisamik
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as far as i know pepsin would degrade the fc fragments, so only the fab portion would be left for the supernatant.
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| sturge_weber
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ssrpk u re right, that pepsin would break in such a way that the Fab portion will remain intact and hence it can still bind the antigen, the confusion is how do we know that klh agglutinates or precipitates. i marked agglutinate, thinkinh klh is a insoluble, but the answer was precipitates, and it says klh is soluble.... so it will precipitate...
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