Hi Francesca, It may be worth trying D2O (rather than H2O) in the final protein buffer. It sometimes causes problems in NMR experiments. One of my colleagues had success with this approach. Crystal screening will need to be done under oil (micro batch) to stop losing D2O by vapor diffusion.
Alun Sent from my Samsung Galaxy smartphone. -------- Original message -------- From: "Mattiroli,Francesca" <francesca.mattir...@colostate.edu> Date:17/02/2015 04:34 (GMT+00:00) To: CCP4BB@JISCMAIL.AC.UK Cc: Subject: [ccp4bb] how to reduce protein solubility Hi all, I am struggling with a protein complex that is too soluble. I have reached about 20 mg/ml but I still observe very little precipitation (clear drops in 90-95% of the tested conditions). The proteins are expressed in insect cells and going to higher concentration is not easily achievable. I have tried different buffer conditions (salt concentration and pH) and I am testing temperatures. I am at a loss with what to try next. Do you think PTMs (phosphorylation, acetylation) might be causing this? Any input on how to decrease solubility? Thank you very much in advance, Francesca
