molla-remove- at mailserver.unimi.it
Wed Mar 28 02:52:14 EST 2001
On Tue, 27 Mar 2001 01:16:48 +0100, ChenHA <hzhen at freeuk.com> wrote:
>.....that they have been able to crystallise some proteins only when the
>his tag is present. From what I was told, it would appeared that the
>his tag helped to make the protein mono-disperse in solution.
Well, so u can consider the problem from a reverse point of view; that
is: keep the HisTag only if u think it is improving some protein
feature(e.g. solubility or stability). About the state of aggregation
in solotion u can check it by DLS of His-tagged and Non-His-Tagged
>This of course doesn't mean that all proteins may benefit from having
>a his tag in their crystallisation, just that some (I stress some)
I agree with you about *some*. Any additional non-structurated amino
acid sequence (i.e. the HisTag) in a protein will probably decrease
the chance of get crystals of it. Obviously this don't mean u'll never
crystallize it; it's only a matter of probability.
The fact that in His-tagged-protein 3D structure the His-Tag itself is
not visible means that it isn't structurated, so it doesn't contribute
in crystal conctacts and eventually it doesn't contribute to stabilize
it (the crystal).
gianluca.molla at uninsubria.it
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