My protein is pretty small ( 10 kDa ), and based on the screening, the space group is R3 with a=b=137.51, c=86.70. Looks to me the cell unit is quite big for such a small protein.Or maybe doesn't matter?
This is actually a mutant, ( the resolution of the wt is 1.8 ).So I need it to be really high resoltion in order to be used in comparison.
On 10/24/06, Mischa Machius <[EMAIL PROTECTED]> wrote:
Jenny - Tassos' message was a bit cryptic, so let me repeat what I think he meant: mosaicity is a parameter that describes to a large part crystal properties, but also beam properties. This means, by using a smaller and well-behaved beam, the mosaicity values will usually be significantly smaller. First of all, I don't think a mosaicity of 1.1 is that dramatic, but smaller values can't hurt (fewer overlaps). Also, depending on your crystal size and morphology, directing the beam to different regions in the crystal will likely also result in different mosaicity values. Generally, the smaller the crystals the better, so the tip is usually a good place to check out. Of course, these are just generalizations that may or may not hold for crystals, but they are aspects to keep in mind. Best - MMOn Oct 24, 2006, at 10:11 AM, Jenny wrote:Thanks for all the replies and I think that's very encouraging.Right now I just used 20% glycerol as the cyro protectant.Looks like I still have quite a few conditions to screen with.I'll try to screen more additives.Thanks, again!
JennyOn 10/24/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Hi, Jenny :
One week is generally considered as good time. From our experience, anything
grows within one day is usually low resolution and high mosaicity. You can try
to use microseeding to get bigger crystals. The way I do is to put some crystals
in 100ul mother liquer and crash them by votexing with a teflon bead and use
this solution to add to your protein solution instead of mother liquer.
I noticed that your crystallization condition is AS. What is your cryo
protectant? Did you try the wet mount to see if you have right cryo protectant?
For AS, I will recommend you to try add 15% or 30% glucose to your mother liqure
and put your crystal in this cryo protectant around 5 mins. Our lab has several
successful experience by using glucose as cyro protectant.
Good luck
Meng-Chiao Joseph Ho
> *** CCP4 home page http://www.ccp4.ac.uk ***
>
>
> 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
>--------------------------------------------------------------------------------Mischa Machius, PhDAssociate ProfessorUT Southwestern Medical Center at Dallas5323 Harry Hines Blvd.; ND10.214ADallas, TX 75390-8816; U.S.A.Tel: +1 214 645 6381Fax: +1 214 645 6353
