His-tagged proteins....

Michael Witty mw132 at mole.bio.cam.ac.uk
Tue Mar 27 06:32:04 EST 2001

On Tue, 27 Mar 2001, ChenHA wrote:
> Michael Witty wrote:
> > On Sun, 25 Mar 2001, ChenHA wrote:
> > > Frank Fuerst wrote:
> > > > But the hist tag might well interfere with crystallization (it might
> > > > even improve it...).
> > > There are anecdotal evidence that suggest that the his tag may help
> > > improve crystallization (and you won't see the his-tag in the
> > > crystal).  Therefore nothing should be removed unless there are
> > > reasons to do so.
> > Dear Chen,
> >          I agree.  But could you tell me if there are any pdb files you
> > know of that DO have the coordinates of a his tag (maybe with Ni in
> > place).  It would be interesting to be able to display one.  Mike.
> I'm afraid I don't have one.  It is interesting that the His tag is in
> fact not seen in the crystal structures of His-tagged proteins I had a
> look at.  I would assume that the his tag is too unstructured to be
> observable.

Dear Chen,
         I am not a great expert, but I think that amino acids at the N
and C termini (where most his tags are) of structures are often not
ordered - I think this is largely due to the fact that those parts are
often not clamped into place by neighbouring parts of the protein.
(ie His tags are not necessarily recalcitrant beasts!).

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