Are you including beam divergence is the defition of mosaicity?
if you are, what happens when you go to a synchrotron?
i.e., we know what happens: the beam is less divergent and hence your spots
sharper.
in any case you will have probably quite a bit better resolution from the
extra photons at a synchrotron source.
+ you could try oil, e.g. paratone-N (for cryo protection), this does not
penetrate the crystal and hence destroy the crystal contacts either.
probably someone suggested the obivous additive screens and changing the
PEG/salt etc.
hth,
tk
Quoting Christian Biertuempfel <[log in to unmask]>:
> Hi Sajid,
> Just a simple test for your problem: Incubate your crystal longer in
> your cryo/stabilization solution. This helps sometimes to lower
> mosaicity. Of course, you can also try co-crystallization with glycerol
> (2%, 5% or 10%).
>
> Good Luck,
> christian
>
>
> sajid akthar wrote:
> > 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/
> >
> >
> >
> ------------------------------------------------------------------------
> >
>
>
> _______________________________________________________________________
>
> Dr. Christian Biertümpfel
> Laboratory of Molecular Biology
>
> NIDDK/National Institutes of Health phone: +1 301 402 4647
> 9000 Rockville Pike, Bldg. 5, Rm. B1-03 fax: +1 301 496 0201
> Bethesda, MD 20892-0580
> USA
> _______________________________________________________________________
>
>
--
Tommi Kajander, Ph.D.
Macromolecular X-ray Crystallography
Research Program in Structural Biology and Biophysics
Institute of Biotechnology
P.O. Box 65 (Street address: Viikinkaari 1, 4th floor)
University of Helsinki
FIN-00014 Helsinki, Finland
Tel. +358-9-191 58903
Fax +358-9-191 59940
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