[Protein-analysis] Re: problem of concentrating protein

Dr Engelbert Buxbaum via proteins%40net.bio.net (by engelbert_buxbaum from hotmail.com)
Wed Jan 16 14:18:19 EST 2008

Am 10.01.2008, 01:01 Uhr, schrieb <sandy_zhu_2006 from hotmail.com>:

>     The protein I am purifying is a kind of zinc finger protein which
> has 81 amino acid and its theoretical pI is 9.19.But after purified
> with Hitrap Heparin column the target protein were still stable,then
> when I use the binding buffer(20mM Tris,10mM Mer,100mM NaCl and 1mM
> ZnCl2,pH 7.0)to dialyze in order to remove the 2M NaCl which were used
> in eluting the protein from the Heparin column, I found that there are
> many sediment in it.
> How to solve this problem?Is there any buffer which is more siutable
> than Tris? Since at pH7.0 Tris is not as efficient as it was.
>    Plus I tried phosphate buffer,but it will interact with the ion
> zinc (within zinc finger protein) and produce sendiment too.

What is the composition of your elution buffer? Does it contain Zn? Does  
the precipitation also occur when the binding buffer does not contain Zn?

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