Hi Katja, If your protein preparation did have salt, you could try lowering that salt (if your protein tolerates) and grid search with varying (increasing) PEG concentrations. Seeding and Additives should really help. the effect/outcome is difficult to predict but these two techniques are helpful in different cases/extent. you could give it a try. good luck also temperature is a under-utilized variable in crystallization, you could see if that has a drastic/favorable effect
Regards, Karthik On Thu, Nov 19, 2009 at 8:39 AM, Jan Schoepe <j.scho...@yahoo.de> wrote: > Hi Katja, > > it makes perfect sense to add a buffer to your assay. Of course for the > beginning something which buffers well around pH 7 like HEPES, BTP, etc. > would be appropriate. If your purification protocol is optimized I would not > change the conditions of the purification buffer. But this might change > maybe if your crystallization experiments give you some more hints about the > solubility of the protein. > > Good luck, > Jan > > > --- Katja Schleider *<katjaschlei...@yahoo.de>* schrieb am *Do, > 19.11.2009: > * > > * > Von: Katja Schleider <katjaschlei...@yahoo.de> > Betreff: [ccp4bb] off-topic: crystal optimization without buffer > An: CCP4BB@JISCMAIL.AC.UK > Datum: Donnerstag, 19. November 2009, 10:33 > > * > Hi everybody, > > sorry for my off-topic question. I got small initial crystals in 200mM > NaSulfat and 20% PEG 3350. > There is no buffer in this condition. How can I optimize these crystals? > Just vary the PEG concentration? Or should I add a buffer; or vary the pH > of the buffer the proteinsolution was in? > > Thank you and best regards, > > Katja > * > * > > >
