Re: [phenixbb] Phenix.refine ignores ligand planarity restraint

Excellent point! Have a look at *.geo file that lists absolutely all geometry restraints that are used in refinement (bonds, angles, torsions, planes, chirals, non-bonded, ncs, etc..). If the plane in question is not listed there then we will need to investigate why is that. Pavel On 2/28/17 09:01, Tim Gruene wrote:

Dear Maike,

did you read the log file to see whether any of your restraints get acknowledged by phenix.refine? There can be many reasons why they are not, e.g. mismatching atom names, mismatching residue abbreviation, ...

Regards, Tim

On Tuesday 28 February 2017 04:44:43 PM Maike Bublitz wrote:

...

Dear all,

thank you again for all your suggestions. Here’s what I’ve tried, without success:

1) reduce deviation from planarity restraints to very small value or zero -> ligand still gets distorted in refinement

2) Set all bond angle restraints to ideal values and checked sums of angles in planar rings -> ligand still gets distorted in refinement

3) Used phenix.elbow with - -final-geometry on a pdb of a planar ligand —> ligand still gets distorted in refinement

4) Used the grade server (grade.globalphasing.orghttp://grade.globalphasing.org) to generate cif file from SMILES string—> phenix.refine stops with message “Unknown file format: grade-ligand.cif”.

Does anyone have another suggestion, except for installing an extra QM package?

Best, Maike

On 27.Feb 2017, at 17:24 , Dale Tronrud mailto:[email protected]> wrote:

You could also check that the other restraints in your cif are compatible with planarity. If the sum of the three bond angles for a planar atom is less than 360 deg your angle restraints will be fighting with your planarity. You also have to check the sum of the internal angles of your planar rings. If I recall correctly the sum of the internal angles must equal n*180 - 360 for the ring to be flat.

Dale Tronrud

On 2/27/2017 9:05 AM, Maike Bublitz wrote: Dear all,

this has probably been discussed many times before, but I just can’t seem to find a solution for my current problem with phenix.refine:

I am trying to refine a protein structure with a rather complex ligand. I’ve generated a .cif file for the ligand with eLBOW, including planarity restraints for its aromatic ring systems. However, phenix.refine keeps on distorting the 6-ring in my indole group, although all respective atoms are included in the plane definition. At a resolution of 3.0 A, I’d very much prefer to impose an ideal planar structure on this ligand.

How can I convince Phenix to not distort my ligand's aromatic rings?

Many thanks for your kind suggestions.

Best regards, Maike

************************************************* Dr. Maike Bublitz Associate Professor of Microbial Biophysics Department of Biochemistry University of Oxford South Parks Road Oxford OX1 3QU United Kingdom phone: +44 (0)1865 613221 lab: +44 (0)1865 613318 maike.bublitz(at)bioch.ox.ac.ukhttp://bioch.ox.ac.uk http://bioch.ox.ac.uk

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************************************************* Dr. Maike Bublitz Associate Professor of Microbial Biophysics Department of Biochemistry University of Oxford South Parks Road Oxford OX1 3QU United Kingdom phone: +44 (0)1865 613221 lab: +44 (0)1865 613318 maike.bublitz(at)bioch.ox.ac.ukhttp://bioch.ox.ac.uk

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