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His-tagged protein and SDS-PAGE migration

Uncle S UncleS at interzon.com
Thu Mar 26 04:06:53 EST 1998

James Bassuk wrote:

> nonsense.  his-tag won't by itself cause nothing more than an increase
> in MW of 600.

Well, the question referred to the pRSET vector.  check it out at 

The tag there comes with all the bells and whistles, EK cleavage,
antibody epitope, to the tune of ~30 residues, not 6.  

> but, being a recombinant protein, all kinds of screwy things can happen.
> your question is too general because every protein would have an
> emperical answer.

Actually, their question is neither nonsense or too general.  They were
just asking if it was possible, which it certainly is.  I don't mean in
the overly literal cop-out sense that every protein can run abberantly. 
I took the question to simply be asking for others' experiences with
his-tagged systems.

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
Dept. of Biochemistry
Box 357742
Universtiy of Washington
Seattle 98195-7742

The difference between love and hate is: hate lasts.

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