Re: [COOT] Bug in coot to change torsion angles?

2022-08-30 Thread Paul Emsley


On 30/08/2022 22:26, Gong, Zhen wrote:


Dear Coot developers and users,

I would like to change some torsion angles of a ligand in coot but it 
did not work as what I expected. I was able to play with the torsion 
angles formed by C06 C07 N08 O10 but not C06 C07 N08 O09 (shown in the 
figure below).




One implies the other, it seems to me.




The restraint file for the torsion angle (C06 C07 N08 O10) is defined 
quite well: LIG CONST_23 O09 N08 C07 C06 -5.58, which is close to 
zero. Therefore, O9, O10 N08 should be more or less in the same plane 
with the benzene ring.




I agree.

By default Coot does not refine torsion angles.

Also torsions named "CONST" are not refined.

You can turn on torsion angle refinement in the R/RC dialog


If I click on the ligand with “real space refinement”, it should make 
the O9, O10 N08 more or less in the same plane with the benzene ring. 
However, coot did not do it.


If you don't have plane restraints for the nitro and ring atoms then 
coot doesn't know (hasn't been told) to keep them planar. All you've 
done is said to Coot "here's a torsion angle, don't use it.|



The corollary of the above is to turn on torsion angle refinement and 
rename the torsion var_23.


You could also add O09 to the ring plane restraint with perhaps double 
or triple the esd.



Paul.




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[COOT] Bug in coot to change torsion angles?

2022-08-30 Thread Gong, Zhen
Dear Coot developers and users,

I would like to change some torsion angles of a ligand in coot but it did not 
work as what I expected. I was able to play with the torsion angles formed by 
C06 C07 N08 O10 but not C06 C07 N08 O09 (shown in the figure below). Is it a 
bug or some geometry knowledge that I do not know?

The restraint file for the torsion angle (C06 C07 N08 O10) is defined quite 
well: LIG CONST_23 O09 N08 C07 C06 -5.58, which is close to zero. Therefore, 
O9, O10 N08 should be more or less in the same plane with the benzene ring. If 
I click on the ligand with “real space refinement”, it should make the O9, O10 
N08 more or less in the same plane with the benzene ring. However, coot did not 
do it.

Can anyone please help? Many thanks in advance!

Best,
Zhen

[cid:image002.png@01D8BC94.06712650]



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