[gmx-users] Residue BGC not found in the database

Justin Lemkul jalemkul at vt.edu
Tue Feb 26 01:10:06 CET 2019

On 2/25/19 4:26 PM, mary ko wrote:
>   Thank you Justin. I am actually following the protein-ligand tutorial to do simulations of my protein-ligand system. I skipped the python cgenff_charmm2gmx.py... Because of the mismatch of cgenff error couldnt be fixed. I have the bgc which is beta-D-glucose and built its .gro file as a ligand and protein-processed.gro and I copied the ligand in the protein-processed.gro to have the complex.gro. I also use charmm36-nov2018 and added it in the force fields with the Bglc to Bgc change in merged.rtp. Now that I try to build the topology.top file with pdb2gmx or even x2top there is an error: atom ot1 in residue Phe was not found in rtp entry Phe with 20 atoms while sorting atoms for pdb2gmx and could only find a force field type for 19078 out of 21750 atoms for x2top. What do you think I should do to build the topology?Thanks.

If you have a protein with BGLC as the ligand, use pdb2gmx and make sure 
there is a TER between the protein and glucose, or otherwise a change in 
chain identifier. Do not use x2top and do not modify merged.rtp (modify 
the residue names in the PDB file instead).


>      On Saturday, February 23, 2019, 6:50:39 PM EST, Justin Lemkul <jalemkul at vt.edu> wrote:
> On 2/20/19 11:19 AM, mary ko wrote:
>> Dear all,
>> I face the 'Residue BGC not found in the database' error when I try to build the topology file of my protein-ligand system by pdb2gmx -f pro.pdb. I used Charmm force field but I tried it with all the other force fields as well to see if the problem could be solved which was useless. I searched the list and errors-gromacs in the website and found that the simplest way is to change the name of this residue. As I am not familiar with protein structure, I do not know what changes may be helpful to pass this error. also, it is said that one way is to parameterize the residue which I do not know how to do that. Your help would be highly appreciated.Thanks!
> If "BGC" is a synonym for beta-D-glucose, that is called BGLC in CHARMM,
> so you just need to rename the residue accordingly. If it is some other
> unknown species, then yes, you need to parametrize it yourself.
> -Justin


Justin A. Lemkul, Ph.D.
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