His Tag purif buffer-to Tris or not to Tris? - best buffer for pH=7.0 (Sep/26/2005 )

I would like to purify the protein whose pI is 7.6. I want to prepare it in the buffer of pH=7.0. people in the lab say that Tris should be used for preparation of the buffers of pH between 7.5-8.5, as its pKa is 8.06, and one must choose a buffer with pKa within 0.5 unit of the desired pH.

So my question is: what buffer is the best for to have a good buffering power at the pH=7.0?

Thank you in advance

Have a look here...