Hi Amit,
I wouldn't worry about acetate depleting the Sm3+. I have tried to
make a derivative of a kinase by soaking ions of lanthanoid series but
in the presence of phosphate buffer and ADP. In this case, lanthanoid
ions are *known* to precipitate with phosphate (and phosphoryl
moiety). I simply spun down the precipitate and took the clear but
colorful supernatant for soaking. A successful ADP-2Ho derivative for
phasing is reported in Acta D 2007 63:493-9. (Failed cases were
rejected by JFCE on April 2.)
Shao-Yang
Quoting "amit sharma" <[log in to unmask]>:
> Dear All,
>
> I have a crystal growing in the presence of 0.1M Sodium Acetate pH 5.0, 10%
> PEG4000, 7.5% Dioxane and 10% Ethylene Glycol. I wanted to know if it would
> be alright to use Samarium chloride for derivatization. I am worried about
> the leaching of samarium by acetate. Also, what soak times can I use and
> what conc. of Samarium chloride? My protein is 10 kDa , has no
> cysteines/methionines and pI for the molecule is 4.6. Also, could somebody
> suggest what other heavy atom soaks could be performed in this case?
>
> Any suggestions would be appreciated.
> Many thanks in advance
>
> --
> Amit Sharma
>
|