pKa of a His tag.

[John Everett]

Artem,

   Thanks for the advice once again.
   The carboxy peptidase sounds interesting
   though I am already cloning in a thrombin
   clevage site adjacent to the His tag.
   The pH of 7.0 or less is indeed to prevent
   amide proton - solvent exchange when the
   sample is in the NMR.

      Thanks,
         John