Dear Guenter,
The first description of the idea behind this technique that I am aware
of is that published almost 10 years ago by a French group under the name of
"'dry' co-crystallisation" in the following paper:
http://dx.doi.org/10.1107/S1399004715010342
Best wishes,
Gerard
--
On Fri, Oct 04, 2024 at 05:40:12PM +0200, Guenter Fritz wrote:
> Hi Amit,
> like Artem wrote below, even despite poor solubility, soaks with
> dried compounds work well (also in our hands).
> We adapted it from the work of T. Barthel, J. Wollenhaupt and
> Manfred Weiss. Also colleagues from industry report good results.
> We add compound dissolved in DMSO to the crystallization well, let
> DMSO evaporate overnight (37° incubator), then put mother liquor on
> top of the dried compound and then the crystals. If all compound
> would dissolve again, final concentration would be 10-50 mM. Soak
> time from 1-2 h to overnight.
> This worked for poorly soluble compounds where we did not succeed
> with soaking in the presence of DMSO.
> Hope that helps!
> Best,
> Guenter
>
> >Dear Amit
> >
> >As David already pointed out, all proteins are different and it's
> >hard to say in advance what amount of DMSO may work (or not).
> >
> >An additional concern is that DMSO can also interfere with ligand
> >binding (cases from my personal past history), especially if these
> >inhibitors/ligands are on the weaker side.
> >
> >Solutions:
> >
> >Despite its very high boiling point (189C) DMSO can in fact be
> >evaporated from a small sample of your inhibitor, resulting in
> >more or less solid inhibitor sample that can be re-dissolved in
> >the same DMSO (but higher concentration), some other solvent, or
> >perhaps directly in the protein solution. The latter is sometimes
> >the only way to do this - I used to set up drops of DMSO
> >solutions, then evaporate the DMSO in high vacuum (heating helps)
> >with a cryofinger, then set up protein drops on top. This of
> >course requires access to a lyophilizer or something similar.
> >
> >If you have a vial of your solution you can freeze-dry DMSO with
> >water, by first diluting the sample then freeze-drying it. Also
> >water can sometimes crash the substance out (if not water, then
> >perhaps Ether or another solvent where your inhibitor does not
> >dissolve) which makes it easier to redissolve (but there will be a
> >loss of course).
> >
> >Find a friendly chemist nearby and ask then to put your sample in
> >a speedvac on 'high BP' setting
> >
> >Notably, if you're "blessed" with an inhibitor that has the
> >general solubility of a Sony Walkman, once you get rid of the
> >DMSO, you may find out that the damned thing does not want to
> >dissolve in anything else, including your protein solution. This
> >happens a lot during early discovery phases when compounds are not
> >very active (micromolar) and also poorly soluble (also
> >micromolar). This is by far the most frequent cause for failing to
> >co-crystallize (or soak) a ligand of interest. Very frustrating.
> >Some success can be achieved using high DMSO or DMF (DMA also can
> >be good) in your crystallization, or by phase transfer catalysts
> >like Cyclodextrin(s) or appropriately formulated micelles. All of
> >which can also mess up crystallization, needless to say.
> >
> >Best of luck in your endeavors!
> >
> >Artem
> >
> >- Cosmic Cats approve of this message
> >
> >
> >On Wed, Oct 2, 2024 at 2:51 PM amit gaur <cdriamitg...@gmail.com> wrote:
> >
> > Hi everyone,
> >
> > I am trying to crystallize a protein with a drug molecule. The
> > protein concentration is 15.5 mg/ml, the drug stock concentration
> > is 10 mM, and the drug is dissolved in DMSO. I am adding the drug
> > to a final concentration of 1 mM in 100 ul of protein, and the
> > DMSO volume is 10 ul for Co-crystallization. I want to know how
> > much DMSO is permissible during co-crystallization with the drug
> > and if DMSO can poison crystal formation. I have not been
> > successful in getting crystals with inhibitors till now, but I
> > obtained crystals of protein without DMSO, and those diffracted to
> > 2.5A.
> >
> > Thanks,
> >
> > *Dr. Amit Gaur,*
> > *Research Scientist*
> > *Center for Biotechnology and **Interdisciplinary Studies,*
> > *Rensselaer Polytechnic Institute,*
> > *1623 15th Street, Troy, NY, 12180*
> >
> > *
> > *
> >
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