In article <mailman.339.1184902875.11350.proteins from net.bio.net>,
"Emily Arturo" <ecgarturo from gmail.com> wrote:
> I am experiencing difficulty with reproducing the oligomerization
> state of a protein overexpressed and purified from E. coli, from prep
> to prep.
> Does anyone have any suggestions?
>> Any other suggestions are welcome...
>> Thank you,
> Emily.
Is the concentration of the protein the same from prep to prep? If the
concentration varies (say better or worse induction) perhaps that alone
is sufficient to favor monomer vs dimer from prep to prep.
You could also try purification strategies that favor keeping high
concentrations if you want dimer or the opposite if you want monomer.For
example gel filtration tends to dilute, ion exchange concentrate etc.
Other possibilities could be subtle changes in buffer composition or
conditions that favor or disfavor oligomerization - changes in ionic
strength, pH, redox state etc.
Roland
