Simon,
solubilize your ligand in DMSO so it is maximally concentrated, 100mM works fine. Add enough compound to achieve 2-3 fold excess to your protein, mix and set up. Make sure your final DMSO concentration is ~3%, otherwise chances are you might harm your protein. If you cannot achieve a high enough stock concentration of DMSO to be below the 3% threshold, dilute you protein in the storage buffer to ~1mg/ml. Add compound to 2-3 fold access, incubate and co-concentrate to the desired concentration. That way you avoid the DMSO shock.
Alternatively you could incubate the concentrated protein with the compound solubilized in water for 24-48hr and hope it is soluble and potent enough to get taken up by the protein and then set up your trays.
HTH
Carsten
> -----Original Message-----
> From: CCP4 bulletin board [mailto:[log in to unmask]]On
> Behalf Of Yue Li
> Sent: Tuesday, December 11, 2007 11:55 AM
> To: [log in to unmask]
> Subject: [ccp4bb] insoluble ligand
>
>
> Hi all,
>
> I have one ligand which is insoluble in water, and I would like to
> co-crystallize it with my protein. Is there any other method
> except for
> dissolving it in DMSO ?
>
> Thanks
>
> Simon
>
>
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