[gmx-users] add new residue and new atom

Malihe Hasanzadeh ml.hasanzadeh at gmail.com
Fri Jan 29 18:22:57 CET 2016


Dear Justin,
Is there any way to get parameters of KCX residue for amber99sb-ildn?
Thanks
Malihe

On Fri, Jan 29, 2016 at 8:45 PM, Justin Lemkul <jalemkul at vt.edu> wrote:

>
>
> On 1/29/16 12:13 PM, Malihe Hasanzadeh wrote:
>
>> Dear justin,
>> I forgot to write this step here, but I did this step also. I added (KCX
>> Protein) in .dat file. But unfortunately as you say the gromacs dosen't
>> identify my new residue!
>>
>
> If this were true, pdb2gmx would not tell you otherwise.  You didn't do
> what you thought you did, or you modified the wrong files.
>
> What should I do? Is my added parameters for KCX residue correct?
>>
>
> Follow the steps exactly in the link I provided.  That's all there is to
> it.
>
> -Justin
>
> Thanks
>> Malihe
>>
>> On Fri, Jan 29, 2016 at 8:26 PM, Justin Lemkul <jalemkul at vt.edu> wrote:
>>
>>
>>>
>>> On 1/29/16 11:52 AM, Malihe Hasanzadeh wrote:
>>>
>>> Hi
>>>>
>>>> I used a PDB structure for MD simulation which it has a carbamylated Lys
>>>> (KCX 220). This residue via carbamyl group bonded to metal in active
>>>> site.
>>>> So I had to define new residue(KCX), I copied parameters of Lys residue
>>>> and
>>>> added carbamyl group and added to .rtp file in amber force field
>>>> (99sb)(gromacs5.0.4). I bring KCX parameters in below:
>>>>      [ KCX ]
>>>>    [ atoms ]
>>>>        N    N           -0.34790     1
>>>>        H    H            0.27470     2
>>>>       CA    CT          -0.24000     3
>>>>       HA    H1           0.14260     4
>>>>       CB    CT          -0.00940     5
>>>>      HB1    HC           0.03620     6
>>>>      HB2    HC           0.03620     7
>>>>       CG    CT           0.01870     8
>>>>      HG1    HC           0.01030     9
>>>>      HG2    HC           0.01030    10
>>>>       CD    CT          -0.04790    11
>>>>      HD1    HC           0.06210    12
>>>>      HD2    HC           0.06210    13
>>>>       CE    CT          -0.01430    14
>>>>      HE1    HP           0.11350    15
>>>>      HE2    HP           0.11350    16
>>>>       NZ    N3          -0.38540    17
>>>>      HZ1    H            0.34000    18
>>>>      HZ2    H            0.34000    19
>>>>      HZ3    H            0.34000    20
>>>>        C    C            0.73410    21
>>>>        O    O           -0.58940    22
>>>>       CX    C            0.73410    23
>>>>       HX    H            0.27470    24
>>>>      OQ1    O           -0.58940    25
>>>>      OQ2    O           -0.58940    26
>>>>    [ bonds ]
>>>>        N     H
>>>>        N    CA
>>>>       CA    HA
>>>>       CA    CB
>>>>       CA     C
>>>>       CB   HB1
>>>>       CB   HB2
>>>>       CB    CG
>>>>       CG   HG1
>>>>       CG   HG2
>>>>       CG    CD
>>>>       CD   HD1
>>>>       CD   HD2
>>>>       CD    CE
>>>>       CE   HE1
>>>>       CE   HE2
>>>>       CE    NZ
>>>>       NZ   HZ1
>>>>       NZ   HZ2
>>>>       NZ   HZ3
>>>>       NZ    CX
>>>>        C     O
>>>>       -C     N
>>>>       CX   OQ1
>>>>       CX   OQ2
>>>>       CX    HX
>>>>    [ impropers ]
>>>>       -C    CA     N     H
>>>>       CA    +N     C     O
>>>>       NZ   OQ1    CX   OQ2
>>>>
>>>> In addition this protein has two Ni ion, that I added its parameters in
>>>> .atp .itp and .dat files.
>>>> Also my ligand has a F ion that when I docked with the protein, it
>>>> closed
>>>> to Ni ion in active site (distance 2.9 A). when I start MD simulation I
>>>> faced with two problems:
>>>>
>>>> 1. when I run pdb2gmx gives many warning:
>>>>
>>>> Identified residue MET1 as a starting terminus.
>>>> Warning: Residue KCX220 in chain has different type (Other) from
>>>> starting
>>>> residue MET1 (Protein).
>>>> Warning: Residue ILE221 in chain has different type (Protein) from
>>>> starting
>>>> residue MET1 (Protein).
>>>> Warning: Residue HIS222 in chain has different type (Protein) from
>>>> starting
>>>> residue MET1 (Protein).
>>>> Warning: Residue GLU223 in chain has different type (Protein) from
>>>> starting
>>>> residue MET1 (Protein).
>>>> Warning: Residue ASP224 in chain has different type (Protein) from
>>>> starting
>>>> residue MET1 (Protein).
>>>> More than 5 unidentified residues at end of chain - disabling further
>>>> warnings.
>>>> Identified residue LEU219 as a ending terminus.
>>>>
>>>> My protein has 570 residue, but as you see the gromacs identified
>>>> residue
>>>> LEU219 as a ending terminus.!
>>>>
>>>> 2. when I used -missing option and continued my simulations, after
>>>> energy
>>>> minimization, I extract em.pdb file and I saw the distance between NI
>>>> ion
>>>> in active site with F ion in ligand is much more ( ~5 A) than before in
>>>> complex.pdb. This means my ligand isn't stable in active site and it is
>>>> moving away!
>>>>
>>>> please help me. what is my mistake?why ligand moving away and why
>>>> gromacs
>>>> doesn't identify end of the protein? Is there a relationship between
>>>> added
>>>> parameters and getting away of ligand?
>>>>
>>>>
>>>> You forgot step 5:
>>>
>>> http://www.gromacs.org/Documentation/How-tos/Adding_a_Residue_to_a_Force_Field
>>>
>>> pdb2gmx writes your custom residue as its own chain, not bonded to the
>>> rest of the protein, so it is its own separate molecule.
>>>
>>> -Justin
>>>
>>> --
>>> ==================================================
>>>
>>> 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
>>>
>>> ==================================================
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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
>
> ==================================================
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> Gromacs Users mailing list
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