Hello Mario,
at 1.9A you might even give S-SAD a try, especially if you have access to an
inhouse source with the flexibility to collect data with a (real) high
multiplicity.
Tim
On Thu, Sep 30, 2010 at 02:40:26PM +0200, Mario Milani wrote:
> Thank you for the suggestions. The data resolution is 1.9 so i can try
> different heavy atoms techniques ... anyway i am really puzzled by the
> peculiar assembly in the crystal and on the possible causes... does anyone
> know about similar cases?
> mario
>
> >
> > Mario,
> > beside what you were mentioning, I would definitely try a quick soak
> > (10-30 seconds) of the crystals in cryo conditions supplemented with
> > halides such as NaBr, or NaI, at pretty high concentrations (say 0.5 M),
> > then directly freezing without backsoak.
> > If the crystals survive the treatment, with that amount of mols per unit
> > cells and surely some good NCS, you should be able to phase pretty easily.
> > Well, of course SeMet would be the other option...
> > ciao,
> > s
> >
> > On Sep 30, 2010, at 1:54 PM, Mario Milani wrote:
> >
> >> Dear all,
> >> i have a 30 kDa protein that crystallize so far in three different
> >> conditions but with the same space group. It initially looks like
> >> tetragonal (I4, a=141, b=141, c=208) and then results triclinic (P1,
> >> a=141, b=141 c=144, alpha=119, beta=119, gamma=90), hosting about 24
> >> mol. in the unit cell. Other data: self rotation shows the presence of 4
> >> peaks with chi=180; molecular replacement shows the presence of a
> >> pseudo-translation peak; DLS made at protein concentration close to
> >> crystal growth conditions shows a Rh compatible with something like a
> >> tetramer with low polydispersity (about 15%). Do you have any experience
> >> with similar ‘asymmetric’ associations? Do you have any suggestions,
> >> beside the addition of ligands to the crystal growth conditions, in
> >> order to get a ‘simpler’ crystallographic assembly? I have some models
> >> (with sequence identity less than 25%) in order to try MR but all trials
> >> so far did not solve the structure (using balbes, molrep, phaser and
> >> epmr). Any suggestion is welcome.
> >> Thank you,
> >>
> >> Mario Milani
> >
> >
> > --
> > Sebastiano Pasqualato, PhD
> > IFOM-IEO Campus
> > Dipartimento di Oncologia Sperimentale
> > Istituto Europeo di Oncologia
> > via Adamello, 16
> > 20139 - Milano
> > Italy
> >
> > tel +39 02 9437 5094
> > fax +39 02 9437 5990
> >
> >
--
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
phone: +49 (0)551 39 22149
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