Dear dengzq1987 (Gmail Research Institute?) You could use ammonium acetate as the solubilizing salt. It evaporates as ammonia and acetic acid, so that the ionic strength is gradually reduced by vapor diffusion. You would then have e.g. PEG in the reservoir and added to the drop, and you could also supply the reservoirs with another salt to get a proper water flow in the experiment. I think that several protein:DNA complexes ahve been crystallized like this, although I have no specific references at hand.
On your fist question for ssDNA length - hard to say from the info you provide. I suggest you go first for a minimal length that still ensures a high affinity complex, i.e. a trimmed comlex yet intact on the functional relevance as one would prefer for any protein construct also. Systematic DNA variations apply foremost to dsDNA complexes where the DNA length and ss overhangs are critical rationales in crystallization screening with the dsDNA typically forming a "selfassembled" scaffold in the crystal Poul > Hi all, > I want to sovle the structrue of ssDNA -protein complex.but the protein are > unstable at low salt concentration,so we use 1M Nacl in the buffer. the high > salt content may disrupt the complex.and I > don't know which ssDNA lenght try fist.any suggestion or experience are > welcome. > > > thank you! > 2010-10-31 > dengzq1987
