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Dear Robbie,
  Thank you for your suggestions. The structure is an all alpha-helix 
structure. I
checked an older version with low z-score also but a little better: -5.8. This
older structure has R and R-free of 0.28 and 0.31 respectively and the final
structure has R and R-free of 0.17 and 0.20 respectively. I think the structure 
is
refined well because procheck give a reasonable G factor of 0.2 and ramachadran
plot is ok (99.9% residues in core and additional allowed regions).


In your mail:
>From: "R.P. Joosten" <[EMAIL PROTECTED]>
>Reply-To: 
>To: ZhiYi Wei <[EMAIL PROTECTED]>
>Subject: Re: [ccp4bb]: whatcheck report an error
>Date:Mon, 05 Dec 2005 09:48:49 +0100
>
>Dear ZhiYi,
> 
> The backbone conformation check is a reasonably good quality indicator. 
> We see that it has improved over time. I.e. newer structures have on 
> average a better backbone quality. We have recently seen that rerefining 
> old structures (decreasing both R and R-free) from the PDB can also give 
> a better backbone score.
> I do not know what kind of structure you are working on, nor do I know 
> what you R and R-free stats are. If they indicate overrefinement, you 
> may want to take a few steps back in your refinement process. Check a 
> few older versions of you structure to see the evolution of the backbone 
> score.
> 
> Best wishes,
> Robbie Joosten
> CMBI, Nijmegen
> The Netherlands
> 
> 
> ZhiYi Wei wrote:
> > ***  For details on how to be removed from this list visit the  ***
> > ***          CCP4 home page http://www.ccp4.ac.uk         ***
> > 
> > 
> > Hi, all
> > 
> > I met a problem during check my structure (160aa, 1.5A resolution) by
whatcheck,
> > which gave out an error:
> > 
> > # 73 # Error: Backbone conformation Z-score very low
> > A comparison of the backbone conformation with database proteins
> > shows that the backbone fold in this structure is very unusual.
> >  
> >  Backbone conformation Z-score : -6.877
> > 
> > I wondered if it should be worried about.
> > 
> > Any suggestion?
> > 
> > Thank you in advance.
> > 
> > I am sorry if you received this mail twice.
> > 
>




------------------------------
Zhiyi Wei
---------------------------------------------
Institute of Biophysics, Chinese Academy of Sciences
15 Datun Road, Chaoyang District
Beijing, P.R.China, 100101
---------------------------------------------
School of Life Sciences,
University of Science & Technology of China,
Hefei, Anhui, P.R.China, 230026
Tel:86-551-3607334
Fax:86-551-3607154

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