DNA binding protein purification

Dear all
Presently I am trying to purifying a DNA binding protein from E.coli..and
trying to remove the contaminating DNA...
I am using DNAse to remove the contaminating DNA ....but the protein is
precipitaing in the contact with diavalent cations used for DNAse
activity...if any one have suggestions plz feel free to share....


itisam

[MatthewDooley]

I have not any suggestion for you but if you get success in your work than please describe it here that how it works?

[Felicia]

Raise NaCl to 1 M or higher and try PEI or streptomycin sulfate precipitation.

[cryo]

what protein is it?

Have you tried heparin column?

[Felicia]

Raise [NaCl] to sufficiently high to dissociate the protein from DNA but low enough so that DNA can still bind to an anion exchange column (in the case of Q sepharose, lower than 600 mM NaCl. Put your lysate through the column and your protein will be in the flow-through. The caveat is that if the amounts DNA in your lysate exceeds column capacity, you'll end up still having DNA in the FT. I personally also prefer PEI or streptomycin.

[tomwatson]

Protocols and tips in protein purification or How to purify protein in one day. Purification of DNA-binding proteins.

[logan12]

Well, nice topic. But got no answer regarding these. If anybody knows, please post it over here.