Sodium Sulfate Precipitation Problem

[shifali chatrath]

Try pptn. with ammonium sulphate ( abt. 33% for IgG) I have done that! It gives good results. Add slowly, keeping constantly stiriing on ice. Then keep stirring in cold room overnight and the ppt.( NIce pellet)after 10K spin at 4C for 30 minutes, can then be dissolved in water and dialized against whatever buffer you want!
Hope it helps!
Shifali

On Tue, 03 Mar 2009 WS wrote :
>Dear Colleagues,
>
>I am about to precipitate some purified IgG by dialysis against 18% m/
>v sodium sulfate (as I want to label the protein with an amino
>reactive reagent, I cannot use ammonium sulfate, it's a convenient
>quencher). I get a huge amount of precipitate after incubating at room
>temp over night. However, the precipitate is floating on top of the
>solution, especially after centrifugation (2000g for 20 min at 25
>degC).
>Any idea how I could obtain an ordinary pellet where one would expect
>it?
>
>Many thanks and best regards,
>
>Wolfgang
>_______________________________________________
>Methods mailing list
>Methods from net.bio.net
>http://www.bio.net/biomail/listinfo/methods


Shifali Chatrath
Graduate Student
Protein science Lab
Dept. of Biological sciences
National University of Singapore
Singapore
+65-65161210
+65-96393449