Dear Dee,
Some proteins with chaperone-like activity (perhaps your B?) can
only bind to partially folded proteins.
Probably A folds to a molten globule structure after 1-2 days. You
can check by spectroscopic techniques (ANS or Trp fluorescence,
CD).
Hope that helps.
Cheers,
Clement
On 10/22/13 11:10 AM, Xiaodi Yu wrote:
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Dear All:
I have a general question about protein- protein interactions. I
have two proteins, A and B. A is a disordered protein while B is
a well folded protein. The binding between A and B has been
approved by GST-pull down assay previously. The strange thing is
I cannot get them bind if protein A were just freshly prepared.
However, if I kept these two proteins separately for one or two
days at 4 degree and then did the GST-pull down assay again, I
can observe very strong interaction between A and B.
Protein A doesn't contain any cys residue. I have already test
certain chemicals which might affect the interactions, for
example, DTT and EDTA. These chemicals seems to have no effect
on the binding.
Although A is a disordered protein, does it need such long time
to find its proper conformation?
Do any people have similar experience? Any suggestions are
greatly appreciated.
Thanks,
Dee