[gmx-users] no residue type with Amber99SB-ILDN ff

[Justin Lemkul]

On 2/6/15 7:58 AM, Ahmet yıldırım wrote:
> 4 letter residue names of termini in pdb file are in the columns 18-22. I
> think they are correct columns?
>

The problem, from the error message, is that you have a standalone LYS (a 
zwitterion), so it is (in a sense) both NLYS and CLYS.  The Amber force fields 
(as implemented) can't handle such a species due to modifications of backbone 
charges when applying N- and C-terminal modifications.  To use this force field 
with this system, you need to introduce a new residue that defines the 
zwitterion correctly.

-Justin

> 2015-02-06 13:15 GMT+01:00 Mark Abraham <mark.j.abraham at gmail.com>:
>
>> On Fri, Feb 6, 2015 at 12:43 PM, Ahmet yıldırım <ahmedo047 at gmail.com>
>> wrote:
>>
>>> Dear users,
>>>
>>> I get the following error when i use pdb2gmx tool of GROMACS 4.6.5, with
>>> the AMBER99SB-ILDN ff. My command:
>>> pdb2gmx -f protein.pdb -o protein.gro -p protein.top
>>>
>>> Fatal error:
>>> In the chosen force field there is no residue type for 'LYS' as a
>>> standalone (starting & ending) residue
>>>
>>> The pdb2gmx gives this error though terminal residues are prefixed with N
>>> and C.
>>>
>>
>> Maybe those prefixes are in the wrong columns of your input .pdb file.
>>
>>
>>> Could there be something wrong with the input .pdb file? But i dont get
>>> this error with another forcefield, 43a2.
>>>
>>
>> GROMOS force fields handle termini differently from AMBER, so that's
>> expected.
>>
>> Mark
>>
>>
>>>
>>> --
>>> Ahmet Yıldırım
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>
>
>

-- 
==================================================

Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

==================================================