Different pH for elution of non-specific Ni column interaction

[Bazeille Nicolas]

Hello everybody,

The elution of my His tag protein contain several contaminants which I want to
eliminate. Reading the forum, I've seem that some E.Coli proteins have been to
defined to be responsible of contamination : methyl transferase, HSP 70 cAMP
receptor, Glucosamine 6 P synthase and FK 506 binding protein. Indeed, I can
some contaminant bands on SDS-PAGE. After a theorical estimation of their own
PHi, I want to try to especially elute them using for Glucosamine 6 P synthase
a buffer like [40 mM MES pH 6,1 500 mM NaCl, 10 % Glycérol, 20 mM Imidazole].
For HSP & FK 506 : [40 mM MES pH 5,1 500 mM NaCl, 10 % Glycérol, 20 mM
Imidazole].

According to yours opinions, is it a good solution to involve my protein
purification which possess a theorical pHi of 8.02 and an elution at about 500
mM imidazole.

Thanks a lot.

Nicolas BAZEILLE Student LBPA Cachan (94) France.