Re: [ccp4bb]: Cys modification

[Laurence Pearl <l.pearl@icr.ac.uk>]

***  For details on how to be removed from this list visit the  ***
***    CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html    ***



What you have is probably cysteic acid, which is the terminal oxidation
product of cysteine. Replace the SH with SO3 and you will probably fit the
density rather well.

Laurence Pearl


David MANDELMAN wrote:

> ***  For details on how to be removed from this list visit the  ***
> ***    CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html    ***
>
> Hi all,
>
> Having recently seen the subject of Cys modification pass thru this
> group, I thought I might throw out another question regarding possible
> thio modifications to Cys.  I have been inspecting 1.6 Ang. electron
> density maps and  have found  supplementary electron density on the end
> of a cysteine in a protein structure.  This structure is virtually
> complete, r=16 and r-free of 19. The electron density is continuous from
> the sulfur and forms a planar, triangular structure that could
> accomodate 2 to 3 more atoms. The density is apparent in both the 2fofc
> and fofc maps. Has anyone out there ever encountered anything like this
> before?  What is even more bizarre is that this density is apparent from
> data collected at room temp., whereas data collected cryogenically does
> not contain this modification. Thanks in advance for any suggestions,
>
> Dave
>
> -----------------------------------------------
> Si on ne peut plus tricher avec ses amis, ce
> n'est plus la peine de jouer aux cartes.
>                              - Marcel Pagnol -
> -----------------------------------------------
> Dr David MANDELMAN
> IBCP - CNRS UMR 5086
> 7, Passage du Vercors
> 69367 Lyon cedex 07 - France
> Tel: 33 (0)4 72 72 26 28
> Fax: 33 (0)4 72 72 26 01
> d.mandelman@ibcp.fr
> http://www.ibcp.fr/team_rh.html
> -----------------------------------------------

--

---------------------------------------------------------------------------
  Laurence H. Pearl

  Section of Structural Biology, Institute of Cancer Research
  Chester Beatty Laboratories,  237 Fulham Road
  London SW3 6JB, UK

  Phone +44-207-970 6045 : Secretary +44-207-970 6046
  FAX   +44-207-970 6051 : E-Mail l.pearl@icr.ac.uk
---------------------------------------------------------------------------
  " Live Simply and do Serious Things .. " - Dorothy Crowfoot Hodgkin
---------------------------------------------------------------------------