Re: [ccp4bb] MR problem --molrep

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: MR problem --molrep
From: Carl Soja allbette {- at -} GMAIL {- dot -} COM
Date: 2008-07-25

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Subject: space group stats
From: "Van Den Berg, Bert" Lambertus {- dot -} VandenBerg {- at -} UMASSMED {- dot -} EDU
Date: 2008-07-25

Subject: Re: MR problem --molrep
From: Roger Rowlett rrowlett {- at -} MAIL {- dot -} COLGATE {- dot -} EDU
Date: 2008-07-25

Carl Soja wrote:
> Dear all
>
> I tried to solve one structure by ccp4i molrep(resolution at 3.0 A,
> space group C222, sequence ID 30%). I can get a good Rfactor 0.528 at
> first translation function. However, the second translation function
> Rfac is 0.526, the third is 0.525, the fourth is 0.525. All of
> the translation function Rfacs are too closed. I changed the model
> and minimum resolution for search, the Rfactor closed no any improved.
> My structure estmates four molecules in the aymmetric unit. This is
> my first time found the closed Rfac by molrep. From the low
> translation function Rfac, it seems that it is correct solution. I
> checked the solution and found some clashes in the structure.I am not
> sure why the Rfactor too closed in next the molecule search? I know
> this is unusual solution by molrep. Does it mean the diffraction data
> has problem?
> Any suggestions are welcome.Thank you in advance!
>
> Carl soja
To be honest, I would try both Phaser and EPMR (now Open-EPMR) first to
do MR. Both especially excel at finding good MR solutions for multimers,
and are very fast as well. These programs can find solutions that are
very difficult to find using other rotation-translation programs,
including MOLREP. In my experience (using Phaser and EPMR) reasonable MR
solutions almost always have an R-factor under 50%.

Cheers,

--
------------------------------------------------------------------------
Roger S. Rowlett
Professor
Colgate University Presidential Scholar
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346

tel: (315)-228-7245
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email: rrowlett@mail.colgate.edu

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: MR problem --molrep
From: Carl Soja allbette {- at -} GMAIL {- dot -} COM
Date: 2008-07-25

Next message:
Subject: space group stats
From: "Van Den Berg, Bert" Lambertus {- dot -} VandenBerg {- at -} UMASSMED {- dot -} EDU
Date: 2008-07-25