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- - Did you check the diffraction at room temperature? The cryo protectant
might increase the mosiacity.
- - You can try to make the crystals grow more slowly:
- different temperature
- different pH
- lower protein concentration
All these things in combination with micro seeding
- - Have you tried the additive screens (e.g. Hampton Research)?
Did you check the quality of those small crystals? It might be worth
waiting for them to grow a little bigger or use them for macro seeding.
And, yes, purity can make a big difference, e.g. an extra purification
step. But I am sure there are also counter examples where an impurity made
the crystals grow.
Finally, 1 week is not so slow for growing crystals, and 3.1A is not so
bad at all (for a protein), at least it might be enough for solving the
structure and then do some mutagenesis based on what you see in the
structure.
Tim
- --
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
On Mon, 23 Oct 2006, Jenny wrote:
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Hi, All,
I just got a crystal and checked it can diffract.However, the
resolution is low (3.1 A) and the mosaicity is about 1.1.Right now the
crystallization condition is quite simple, just use the AS with
several acid pH. Is there anything I can do for the next step to
improve the mosaicity and then hopefully improve the resolution?Is it
related to the purity of my protein?When I set up trays, I noticed
that the big crystals come from the impure sample.I only got tiny
crystals from one of the pure sample and it grows really slow ( ~ 1
week ).
Thanks very much.
Jenny
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