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Just a possibility for salvage of your already set-up drops: You can spike the reservoirs with some highly concentrated precipitant (no matter what as long as it sucks more water out of your drop). It does not solve your problem but maybe you can revive a few drops and get more information from your experiment. I use a syringe with a needle and poke through the tape into the reservoir and top it off with the high conc. precip. The tiny hole is easy to re-tape and does not hinder observation. Best, BR From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Mattiroli,Francesca Sent: Tuesday, February 17, 2015 5:23 AM To: [log in to unmask] 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