What is the room temperature diffraction like? If that's good, you might like to optimize cryo. If I am not mistaken, PEG 3350 has been reported to cryoprotect at 20-35% with or without 5-10% glycerol. You might also like to try including some glycerol in the mother liquor--it may better crystal tolerance of glycerol as cryoprotectant.
Sincerely, Navdeep --- Navdeep Sidhu Graduate Student University of Saskatchewan --- Quoting sajid akthar <[EMAIL PROTECTED]>: > > 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/ >
