Are you including beam divergence is the defition of mosaicity? if you are, what happens when you go to a synchrotron?
i.e., we know what happens: the beam is less divergent and hence your spots sharper. in any case you will have probably quite a bit better resolution from the extra photons at a synchrotron source. + you could try oil, e.g. paratone-N (for cryo protection), this does not penetrate the crystal and hence destroy the crystal contacts either. probably someone suggested the obivous additive screens and changing the PEG/salt etc. hth, tk Quoting Christian Biertuempfel <[EMAIL PROTECTED]>: > Hi Sajid, > Just a simple test for your problem: Incubate your crystal longer in > your cryo/stabilization solution. This helps sometimes to lower > mosaicity. Of course, you can also try co-crystallization with glycerol > (2%, 5% or 10%). > > Good Luck, > christian > > > sajid akthar wrote: > > Dear All > > > > My protein size is ~30kD and crystallizes with > > 19%Peg3350, 0.2M Nacl, and 0.1M Na Cacodylate buffer. > > > > Please refer the attached crystal image with this. The > > crystal looks like good enough for home source. These > > crystals appears in 4-5 days at room temp. > > > > Sometimes I'm getting crystals like this, but very few > > in 24 well tray. Most of the time, I found the drop > > contains needles. If I reduce the precipitant little > > bit, I wont find any change in the drop even after > > long time. Changing pH (or temp)of the buffer does not > > help me any better. The crystal appears only around > > 5.5pH. > > > > The problem is mosaicity. This crystal diffracted in > > home source upto 3.2A and the mosaicity is 2.5degree. > > Almost all the good crystal like this having same > > mosaicity. > > > > Good cryo condition so far that I found was > > 10%Glycerol with mother liquor. Other conditions > > weekens the diffraction quality or increase mosaicity. > > > > In many crystal I could see some crack in the middle > > of the crystal, it looks like twin crystal. Or the > > crystal appears with some sattelite crystals. > > > > Can anyone suggest me some good way to overcome these > > problems. > > > > Thankz > > > > Sajid > > > > > > > > From Chandigarh to Chennai - find friends all over India. Go to > http://in.promos.yahoo.com/groups/citygroups/ > > > > > > > ------------------------------------------------------------------------ > > > > > _______________________________________________________________________ > > Dr. Christian Biertümpfel > Laboratory of Molecular Biology > > NIDDK/National Institutes of Health phone: +1 301 402 4647 > 9000 Rockville Pike, Bldg. 5, Rm. B1-03 fax: +1 301 496 0201 > Bethesda, MD 20892-0580 > USA > _______________________________________________________________________ > > -- Tommi Kajander, Ph.D. Macromolecular X-ray Crystallography Research Program in Structural Biology and Biophysics Institute of Biotechnology P.O. Box 65 (Street address: Viikinkaari 1, 4th floor) University of Helsinki FIN-00014 Helsinki, Finland Tel. +358-9-191 58903 Fax +358-9-191 59940
