[ccp4bb]: Re: Molecular Replacement in F23

[David A Robinson <davidar@chem.gla.ac.uk>]

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HI there,

I also had problems with molecular replacement in F23. The structure I was  
trying to solve was dodecameric, but with 1 mol in the AU (i.e. the
dodecamer was formed by the symmetry operataions), therefore extensive 
crystal contacts.

In AMoRe the rotation function gave very poor results, therefore the
resulting transaltion searchs gave poor solutions (CC < 20%, R > 60%)
I used 3 different search models (full and poly-Ala) and the results were
similar.  

The molecular replacememt was solved with EPMR, using a poly-alanine
search model,(CC 35%, R 52%)

For the successfull EPMR run I increased the population size to 400 per
generation, and used a minimum bump radius equal to the radius of the
search model 

EPMR takes a while to run, but in cases where AMoRe has not
worked in our group, EPMR has brought some success.


all the best

david robinson

**************************************************************
David A Robinson
Protein Crystallography		e-mail: davidar@chem.gla.ac.uk
Dept. of Chemistry		
Joseph Black Building		tel: 0141 330 6180
University of Glasgow		fax: 0141 330 4888
Glasgow
G12 8QQ
**************************************************************

On Tue, 3 Sep 2002, OnLineHelpForm wrote:

> I am using ccp4 version  release-4_1_1.
> I am using ccp4i.
> I am using the redhat71 operating system.
> My compiler is: native
> More on my compiler: gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-98)
> I installed using compilesource
> The problem is as follows:
> Hi, 
> 
> Has anyone had any experience in solving a molecular replacement solution with a F23 or F432 space group? I would appretiate any advice.
> 
> 
> 
> 
> Thanks in advance,
> jayita, guhanija@umdnj.edu
> 
>