His.tags and weird sequencing

Jared Head bijgh at zeus.bris.ac.uk
Tue Jun 30 05:00:28 EST 1998


Hi,

I've been using pet 15b to express a number of his.tagged proteins for
ages without any problems, but I've sent some of the protein to a
colleague who had it N-terminal sequenced, and where we were expecting
[MGSSHHHHHHSSGLVP...] we got just [SSGLVP...] so it appears all the
histidines have disappeared.  I purified the protein on a Ni column, so
the histidines *were* there (and previously DNA sequencing and thrombin
cleavage have confirmed the presence of the full tag for this plasmid),
and my friend swears he hasn't done anything to the protein that could
cleave off part of the tag.

Has anybody got any ideas about what might have happened

Jared

-- 
Jared Head at the Department of Biochemistry, University of Bristol

         "Life is something to do when you can't get to sleep." 
                                                   Fran Lebowitz




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