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Re: [ccp4bb] Solubility of ligands
 

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CCP4bb <-- 2007 <-- February 2007 <-- 28 February 2007
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Subject: Solubility of ligands
From: I {- dot -} moustafa {- at -} PSU {- dot -} EDU
Date: 2007-02-28 		Next message:
Subject: Re: process SeMet labelled data
From: vanraaij {- at -} USC {- dot -} ES
Date: 2007-02-28


Subject: Re: Solubility of ligands
From: knettles {- at -} SCRIPPS {- dot -} EDU
Date: 2007-02-28
Hi Ibrahim,

I think solubility is overrated.

We routinely obtain structures from protein solutions with a big pellet of
ligand in the bottom of the tube. For co-crystallizations we add 1mM
compound to a 0.3mM solution of the protein and incubate overnight. Many of
the compounds are only soluble to 50micromolar, so we get a lot of
precipitate. The next day, we spin the tube at high speed, and use the
supernatant for crystallization trials. We have started from 100mM stocks in
100% DMSO or ethanol. This has worked for compounds ranging for picomolar to
micromolar affinity, which surprised us, but it worked!

Regards,
Kendall


On 2/28/07 11:28 AM, "Ibrahim M. Moustafa" wrote:

> Dear all,
>
> I have a small library of In-silico screened compounds to test for
> activity and for crystallization trials with our protein of interest.
>
> We only have about 10 mg/ml of each compound. As there is no
> available experimental information about solubility of these
> compounds, I have no choice but to try different solvents.
>
> The first solvent to try will be DMSO (100%) to make the highest
> stock concentration of each compound. My question to those who passed
> through similar experience is:
>
> Assuming some of the compounds turned to be insoluble in DMSO,
> which is possible, how to completely recover the compounds from DMSO
> before trying another solvent.
>
> Will spinning and leaving the tube open over the bench be enough
> to get rid of the solvent or what people usually do in that case?
> What is the recommended solvent to try next?
>
> Is there a standard protocol to follow for the case we have??
>
> thanks in advance for those who are willing to share their experience.
>
> regards,
> Ibrahim
>
> Ibrahim M.Moustafa, Ph.D.
> Pennsylvania State University
> Biochemistry & Molecular Biology Dept.
> 201 Althouse Lab.
> University Park, PA16802
>
> Tel (814) 863 8703
> Fax (814) 865 7927
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