mobility of His-tagged proteins

kevin.bailey at kevin.bailey at
Fri Sep 8 09:06:27 EST 2000

In article <WVNt5.248$v3.2331 at uchinews>, "Emir Khatipov"
<ekhatipo at> wrote:

> Hi,
> My collegue is expressing a short (~7kD = 250bp) His-tagged peptide. He sees
> 2 distinct bands on his SDS-PAGE (Tris-Gly, 4-20% gel), and believes that
> for some reason one band may be the higher MW of the tagged protein, and
> another of the non-tagged one. His Westerns show that the lower molecular
> band is the one of the tagged protein. Would 6His cause increased mobility?
> So far I was aware that 6His may retard the mobility, but these were the
> observations I learned from the web with higher MW proteins (20kD and up).
> Could someone comment on that?
> Thanks
> Emir

			If the proteins are relatively soluble and can be desalted it would be
best to get them mass analysed, this should resolve the matter, perhaps in
addition it may be worth N-terminally sequencing each band to see if both
or just one has the tag (assuming it's an N-terminal His tag).

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