A couple of thoughts:
* We have actually managed to grow quite a few crystals like this.
Sometimes they are not single crystals, but stacks of mis-aligned
plates that come apart easily when handled or subjected to osmotic
stress. Sometimes these stacks give great-looking diffraction
patterns, but they turn out to be multiple lattices :( (You find
this out when you try to index your beautiful diffraction images and
it runs off the rails.) We got around this issue by taking our
crystallization condition and doing a full additive screen
(everything we had in the reagent drawer that looked like an
additive, salts, solvents, etc.) at 50-200 mM or 5-10%. We found a
condition that gave slightly thicker plates that were single
crystals and not stacks of thin plates, and those crystals
cryoprotected and diffracted well.
* If your plates are actually single crystals, but are just fragile or
have high solvent content and are being torn apart by osmotic
stresses introduced by your cryoprotectant, I highly recommend
trying the cryomixes described in Vera & Stura, Cryst. Growth Des.
(2014) 14, 427-435. For crystals grown in PEGs, one or more of these
mixes are like magic with fragile crystals. For salt conditions, 2.5
M lithium sulfate is also very dependable. Saved our bacon for a
couple of high solvent content crystals recently.
Cheers,
_______________________________________
Roger S. Rowlett
Gordon & Dorothy Kline Professor
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
ofc: (315)-228-7395
fax: (315)-228-7935
email: [log in to unmask]
On 4/10/2014 1:59 PM, Anamika Singh wrote:
> Dear All,
>
> I want to get some help regarding crystallization for one of the
> protein I am working. This is a recombinant protein of molecular
> weight of 17.5 kDa.I am getting crystals shape like thin plates in 5
> days, in different conditions like bis tris pH 6.5-8, HEPES pH 6-8
> with .1M nacl , .01M DTT having PEG 3350, PEG 6000 as precipitant. But
> whenever we used to put crystal in cryoprotectant like 20 % ethylene
> glycol, glycerol, MPD it used to split like layers of some tree barks.
> And the crystal which were diffracting not getting diffracted above
> 3.0 Angstrom.
>
> Please help me out.
>
> Thanks in advance
> --
> Anamika
