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His-tagged protein and SDS-PAGE migration

Darren Tyson tysondr.nospam at slu.edu
Thu Mar 26 13:04:30 EST 1998

Uncle S wrote:

> And as Arnoud van Vliet pointed out, it's quite common with His-tagged
> proteins to see significantly higher apparent MWs. I've got one that
> runs %50 higher than its calculated mass. As I told Tunyaplin via email,
> I wouldn't give up on the protein in question until taking a mass of it,
> which is easy and cheap.
> > On Tue, 10 Mar 1998 ct133 at columbia.edu wrote:
> > > Does anybody know whether his-tagged protein expressed from pRSET
> > > vector (Invitrogen) can migrate aberrantly on SDS-PAGE?
> > > C. Tunyaplin
> Shamus Young

 I agree.  I've used a different expression vector to express a His-tagged
protein which
migrated at ~55 KDa on SDS-PAGE but should actually be about 40 KDa strictly
according to calculated mass.

In my expreience, epitope tags can alter the migration of proteins on SDS-PAGE

dramatically (although I've never seen a protein migrate faster than expected
SDS-PAGE... how about anyone else?)


Darren Tyson, Ph.D. Candidate
Cell & Molecular Biology Program
Saint Louis University, St. Louis, MO
tysondr at nospam.slu.edu
(remove nospam. before mailing)

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