Dear Sajid, I have observed a consistent reduction in mosaicity (from approx. 0.95 to 0.45) for one case by freezing the crystals in a cryostream (N2 vapour) as opposed to submerging in liquid nitrogen.
Have others observed this? Daniel > > 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/
