Dear all, I am trying to solve the structure of a transcription factor in complex with its DNA. I got crystals of the complex under different conditions than the protein alone and they also look different. Unfortunately, they only diffract to 6Å so far. Before I continue to optimize the crystals I would like to confirm that the crystals really contain the bound DNA. Thus I tried to crystallize the protein alone under the same conditions as the complex which did not give crystals. I also tried to stain the crystals with methylene blue, but that did not work (but staining with IZIT did not work either). Additionally I dissolved a crystal and measured the absorption. The ratio between A260 and A280 was 1.3. So there seems to be DNA, but less than there should be.
Does any of you know a good way to quickly but reliably confirm the presence of DNA in my crystals? Thanks a lot in advance. Nick
