What to use to elute DNA binding protein from DNA ?

[S Chen Lab]

Hi all,

The mobility of a labeled probe is retarded when incubated with a 
nuclear extract.  I'd like to enrich for the presumed DNA binding 
protein by using tethered DNA to capture that component of the nuclear 
extract.  My question: is there a general buffer to elute (unknown) DNA 
binding proteins from their binding site -- into solution for further 
analysis.   After looking at a couple of random papers at hand, I am 
thinking of 100mM NaOAC 4.2, or simply very high salt like 4M NaCl or 
KCl.   After the protein is in solution, I'd concentrate and exchange 
the buffer for subsequent SDS-PAGE.   All I'd like to see for now is the 
size of the protein.

Thanks for any buffer suggestions.