Mon. July 4th 2011
EBI
Good evening,
firstly, it could be something that came form the buffer/crystallisation
soup etc. What about phosphate?
Secondly, if you think it is a "natural" post-translation modification of
your specific protein this is gene/source depended. Check the uniprot
entry of your protein, UNP does lists the known modification. Is there
a mass-spec analysis?
Miri
On Mon, 4 Jul 2011, Artem Evdokimov wrote:
> Before ruling this a covalent modification, did you check if a sulfate or some other tetrahedral ion (or
> a disordered acetate) fit the bill with respect to distances to the neighboring atoms?
>
> Artem
>
> 2011/7/4 ruheng <[log in to unmask]>
> Dear all,
>
> Recently we are working on an archaebacteria protein which was expressed and purified from
> E.coli by conventional procedures. After we solved the structure, we found that there is an
> extra density in one of the argninine as shown in the attached picture. It seems that the
> density is larger than a methyl group and the atoms in the density are not on one plane. So
> we are curious about whether the density is a kind of posttranslational modification of
> arginine residues in the protein, if it is, what kind of modification could it be? And most
> important, what is the biological significance of this kind modification? Any suggestions and
> dicussions are appreciated!
>
> Best,
> Heng
>
>
>
>
Mon. July 4th, 2011
EBI
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