[gmx-users] Capping residues

Justin A. Lemkul jalemkul at vt.edu
Thu Jul 8 04:14:17 CEST 2010



Sai Pooja wrote:
> Hi Justin,
> 
> I do not have the problem of extra hydrogens or a net charge on the NAC 
> group. 
> 

The net charge is not on NAC, it's on the entire peptide.  If you're not seeing 
it, that makes the bug even more troubling, since it's sporadic.  Are you using 
the latest git version, or an older one?  If it's older, that may help track 
down the code change that is causing problems.

> In relation to the other bugs you have mentioned, would it be a good 
> idea to start a project with this git version of gromacs? The topology 
> file I have now looks fine but I may be missing certain irregularities. 
> Is there a good way to check?
> 

I would never recommend using a git version for production work.  It is under 
continual development (thanks to the hard work of the developers!) and as such, 
small (or large) bugs may get occasionally introduced, or new features added or 
modified.  I would only suggest using a git version for actual data collection 
if it fixes a specific bug that was a problem for you and the git version fixes 
it and is stable.

As far as checking, I have no idea.  The test suite needs to be developed 
further before there is a useful set of tools for validating a GROMACS installation.

> Is there another safe way to use the charmm forcefield with 
> gromacs(without gromacs)?
> 

Supposedly the CHARMM implementation in GROMACS is stable, but maybe changes in 
the code have given rise to the bugs I'm suspecting.  I can't even get a 
topology for lysozyme; there are a host of errors which are concerning to me.

Otherwise use the CHARMM program, or even NAMD.

-Justin

> Pooja
> 
> 
> On Wed, Jul 7, 2010 at 8:48 PM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     Sai Pooja wrote:
> 
>         This probably is my ignorance but the error and the "bug" goes
>         when I replaced CBX with NAC everywhere.
> 
> 
> 
>     I would suggest filing a bugzilla.  I was able to reproduce your
>     problem.  If nothing else, pdb2gmx should not be name-specific.
>      Something very weird is going on.  More troubling, the topology
>     that pdb2gmx generated for me with NAC as the C-terminal cap had a
>     broken net charge of +0.960 - it appears that pdb2gmx is adding
>     double hydrogens to the backbone amides - both H and HN.
> 
>     With the impending release of Gromacs 4.5, this could be a very
>     problematic bug.
> 
>     -Justin
> 
> 
>         On Wed, Jul 7, 2010 at 6:09 PM, Sai Pooja <saipooja at gmail.com
>         <mailto:saipooja at gmail.com> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>> wrote:
> 
>            1. I have only added entries in the .rtp files. Do I need to add
>            them in .hdb and .tdb files too? Could I simply define a new
>            terminal in the aminoacids.c.tdb file?
> 
>            For your reference:
> 
>            *Initial PDB file*
>            ATOM      1  C   ACE     1      12.532  -0.094  26.546  1.00
>          2.10         FR1  C
>            ATOM      2  O   ACE     1      13.443  -0.213  25.696  1.00
>          1.60         FR1  O
>            ATOM      3  CH3 ACE     1      12.782  -0.027  28.022  1.00
>          2.17         FR1  C
>            ATOM      4 HH31 ACE     1      13.138  -0.995  28.375  1.00
>          2.17         FR1  H
>            ATOM      5 HH32 ACE     1      11.856   0.230  28.537  1.00
>          2.17         FR1  H
>            ATOM      6 HH33 ACE     1      13.535   0.733  28.228  1.00
>          2.17         FR1  H
>            ATOM      7  N   VAL     2      11.255  -0.021  26.193  1.00
>          1.60         FR1  N
>            ATOM      8  CA  VAL     2      10.854  -0.210  24.846  1.00
>          2.37         FR1  C
>            ATOM      9  C   VAL     2      11.022   1.197  24.222  1.00
>          2.10         FR1  C
>            ATOM     10  O   VAL     2      10.340   2.192  24.528  1.00
>          1.60         FR1  O
>            ATOM     11  CB  VAL     2       9.401  -0.679  24.711  1.00
>          2.37         FR1  C
>            ATOM     12  CG1 VAL     2       9.113  -0.953  23.274  1.00
>          2.17         FR1  C
>            ATOM     13  CG2 VAL     2       9.141  -1.946  25.547  1.00
>          2.17         FR1  C
>            ATOM     14  H   VAL     2      10.636   0.148  26.935  1.00
>          0.80         FR1  H
>            ATOM     15  N   GLN     3      12.113   1.241  23.470  1.00
>          1.60         FR1     ATOM     16  H   GLN     3      12.656  
>         0.425  23.466  1.00  0.80         FR1     ATOM     17  CA  GLN  
>           3      12.533   2.509  22.812  1.00  2.37         FR1     ATOM
>             18  CB  GLN     3      13.982   2.287  22.560  1.00  2.23  
>               FR1     ATOM     19  CG  GLN     3      14.807   3.474
>          22.166  1.00  2.23         FR1     ATOM     20  CD  GLN     3  
>            16.219   3.156  22.441  1.00  2.10         FR1     ATOM    
>         21  OE1 GLN     3      16.635   2.341  23.295  1.00  1.60      
>           FR1     ATOM     22  NE2 GLN     3      17.095   3.710  21.642
>          1.00  1.60         FR1     ATOM     23 HE21 GLN     3    
>          18.031   3.421  21.665  1.00  0.80         FR1     ATOM     24
>         HE22 GLN     3      16.790   4.446  21.071  1.00  0.80        
>         FR1     ATOM     25  C   GLN     3      11.689   2.846  21.556
>          1.00  2.10         FR1     ATOM     26  O   GLN     3    
>          11.395   3.988  21.389  1.00  1.60         FR1     ATOM     27
>          N   LEU     4      11.403   1.872  20.676  1.00  1.60        
>         FR1     ATOM     28  H   LEU     4      11.747   0.959  20.767
>          1.00  0.80         FR1     ATOM     29  CA  LEU     4    
>          10.606   2.121  19.473  1.00  2.37         FR1     ATOM     30
>          CB  LEU     4      11.011   1.111  18.398  1.00  2.23        
>         FR1     ATOM     31  CG  LEU     4      12.501   1.073  18.020
>          1.00  2.37         FR1     ATOM     32  CD1 LEU     4    
>          12.869  -0.185  17.207  1.00  2.17         FR1     ATOM     33
>          CD2 LEU     4      12.893   2.344  17.332  1.00  2.17        
>         FR1     ATOM     34  C   LEU     4       9.082   2.102  19.484
>          1.00  2.10         FR1     ATOM     35  O   LEU     4      
>         8.400   1.579  20.374  1.00  1.60         FR1     ATOM     36  N
>           CBX     5       8.609   2.722  18.430  1.00  1.60         FR1
>            ATOM     37  H   CBX     5       9.198   3.338  17.946  1.00
>          0.80         FR1
>            ATOM     38 CH3  CBX     5       7.176   2.594  17.895  1.00
>          2.17         FR1
>            ATOM     39 HH31 CBX     5       6.785   1.605  18.135  1.00
>          2.17         FR1  H
>            ATOM     40 HH32 CBX     5       7.178   2.732  16.814  1.00
>          2.17         FR1  H
>            ATOM     41 HH33 CBX     5       6.547   3.355  18.357  1.00
>          2.17         FR1
> 
> 
>            *Changes in .rtp file*
>            [ ACE ]        [ atoms ]
>                    CH3     CT3     -0.270  0
>                    HH31    HA      0.090   0
>                    HH32    HA      0.090   0
>                    HH33    HA      0.090   0
>                    C       C       0.510   1
>                    O       O       -0.510  1
>             [ bonds ]
>                    C       CH3
>                    C       +N
>                    CH3     HH31
>                    CH3     HH32
>                    CH3     HH33
>                    O       C
>             [ impropers ]
>                    C       CH3     +N      O
>            [ CBX ]
>             [ atoms ]
>                   N       NH1     -0.470  1            HN      H      
>         0.310   1            CH3     CT3     -0.110  1            HH31  
>          HA      0.090   1            HH32    HA      0.090   1        
>            HH33    HA      0.090   1      [ bonds ]
>                   -C      N
>                   N       HN
>                   N       CH3
>                   CH3     HH31
>                   CH3     HH32
>                   CH3     HH33
>             [ impropers ]
>                   N       -C      CH3     HN
>                   -C      CH3     N       -O
> 
>            *command:*
>            pdb2gmx -f F1.pdb -q F1clean.pdb -nocmap -v -ss -ter -o
>         work.gro -p
>            work.top
> 
>            *.gro file from pdb2gmx*
>            1ACE    CH3    1   1.278  -0.003   2.802
>                1ACE   HH31    2   1.314  -0.100   2.838
>                1ACE   HH32    3   1.186   0.023   2.854
>                1ACE   HH33    4   1.354   0.073   2.823
>                1ACE      C    5   1.253  -0.009   2.655
>                1ACE      O    6   1.344  -0.021   2.570
>                2VAL      N    7   1.125  -0.002   2.619
>                2VAL     HN    8   1.064   0.015   2.694
>                2VAL     CA    9   1.085  -0.021   2.485
>                2VAL     HA   10   1.142  -0.094   2.447
>                2VAL     CB   11   0.940  -0.068   2.471
>                2VAL     HB   12   0.879   0.005   2.503
>                2VAL    CG1   13   0.911  -0.095   2.327
>                2VAL   HG11   14   0.817  -0.126   2.318
>                2VAL   HG12   15   0.925  -0.012   2.274
>                2VAL   HG13   16   0.973  -0.167   2.294
>                2VAL    CG2   17   0.914  -0.195   2.555
>                2VAL   HG21   18   0.819  -0.223   2.544
>                2VAL   HG22   19   0.974  -0.268   2.523
>                2VAL   HG23   20   0.932  -0.175   2.651
>                2VAL      C   21   1.102   0.120   2.422
>                2VAL      O   22   1.034   0.219   2.453
>                3GLN      N   23   1.211   0.124   2.347
>                3GLN     HN   24   1.266   0.043   2.347
>                3GLN     CA   25   1.253   0.251   2.281
>                3GLN     HA   26   1.240   0.331   2.340
>                3GLN     CB   27   1.398   0.229   2.256
>                3GLN    HB1   28   1.437   0.191   2.340
>                3GLN    HB2   29   1.406   0.161   2.183
>                3GLN     CG   30   1.481   0.347   2.217
>                3GLN    HG1   31   1.469   0.367   2.119
>                3GLN    HG2   32   1.453   0.428   2.270
>                3GLN     CD   33   1.622   0.316   2.244
>                3GLN    OE1   34   1.663   0.234   2.329
>                3GLN    NE2   35   1.709   0.371   2.164
>                3GLN   HE21   36   1.803   0.342   2.167
>                3GLN   HE22   37   1.679   0.445   2.107
>                3GLN      C   38   1.169   0.285   2.156
>                3GLN      O   39   1.140   0.399   2.139
>                4LEU      N   40   1.140   0.187   2.068
>                4LEU     HN   41   1.175   0.096   2.077
>                4LEU     CA   42   1.061   0.212   1.947
>                4LEU     HA   43   1.085   0.309   1.937
>                4LEU     CB   44   1.101   0.111   1.840
>                4LEU    HB1   45   1.076   0.020   1.873
>                4LEU    HB2   46   1.049   0.133   1.757
>                4LEU     CG   47   1.250   0.107   1.802
>            4LEU     HG   48   1.305   0.103   1.886
>                4LEU    CD1   49   1.287  -0.019   1.721
>                4LEU   HD11   50   1.384  -0.017   1.699
>                4LEU   HD12   51   1.267  -0.100   1.775
>                4LEU   HD13   52   1.234  -0.020   1.636
>                4LEU    CD2   53   1.289   0.234   1.733
>                4LEU   HD21   54   1.386   0.231   1.709
>                4LEU   HD22   55   1.235   0.246   1.650
>                4LEU   HD23   56   1.273   0.312   1.794
>                4LEU      C   57   0.908   0.210   1.948
>                4LEU    OT1   58   0.840   0.158   2.037
>                4LEU    OT2   59   0.845   0.235   1.830
>                4LEU    HT2   60   0.746   0.231   1.844
>                5CBX      N   61   0.861   0.272   1.843
>                5CBX     HN   62   0.920   0.334   1.795
>                5CBX    CH3   63   0.718   0.259   1.789
>                5CBX   HH31   64   0.678   0.161   1.814
>                5CBX   HH32   65   0.718   0.273   1.681
>                5CBX   HH33   66   0.655   0.336   1.836
>               1.14840   0.71270   1.21755
> 
> 
> 
> 
> 
> 
>            *PDB file from pdb2gmx using -q option*
> 
>            TITLE     Gromacs Runs On Most of All Computer Systems
>            MODEL        1
>            ATOM      1  C   ACE     1      12.532  -0.094  26.546  1.00
>          2.10              C
>            ATOM      2  O   ACE     1      13.443  -0.213  25.696  1.00
>          1.60              O
>            ATOM      3  CH3 ACE     1      12.782  -0.027  28.022  1.00
>          2.17              C
>            ATOM      4 1HH3 ACE     1      13.138  -0.995  28.375  1.00
>          2.17              H
>            ATOM      5 2HH3 ACE     1      11.856   0.230  28.537  1.00
>          2.17              H
>            ATOM      6 3HH3 ACE     1      13.535   0.733  28.228  1.00
>          2.17              H
>            ATOM      7  N   VAL     2      11.255  -0.021  26.193  1.00
>          1.60              N
>            ATOM      8  CA  VAL     2      10.854  -0.210  24.846  1.00
>          2.37              C
>            ATOM      9  C   VAL     2      11.022   1.197  24.222  1.00
>          2.10              C
>            ATOM     10  O   VAL     2      10.340   2.192  24.528  1.00
>          1.60              O
>            ATOM     11  CB  VAL     2       9.401  -0.679  24.711  1.00
>          2.37              C
>            ATOM     12  CG1 VAL     2       9.113  -0.953  23.274  1.00
>          2.17              C
>            ATOM     13  CG2 VAL     2       9.141  -1.946  25.547  1.00
>          2.17              C
>            ATOM     14  H   VAL     2      10.636   0.148  26.935  1.00
>          0.80              H
>            ATOM     15  N   GLN     3      12.113   1.241  23.470  1.00
>          1.60              N
>            ATOM     16  H   GLN     3      12.656   0.425  23.466  1.00
>          0.80              H
>            ATOM     17  CA  GLN     3      12.533   2.509  22.812  1.00
>          2.37              C
>            ATOM     18  CB  GLN     3      13.982   2.287  22.560  1.00
>          2.23              C
>            ATOM     19  CG  GLN     3      14.807   3.474  22.166  1.00
>          2.23              C
>            ATOM     20  CD  GLN     3      16.219   3.156  22.441  1.00
>          2.10              C
>            ATOM     21  OE1 GLN     3      16.635   2.341  23.295  1.00
>          1.60              O
>            ATOM     22  NE2 GLN     3      17.095   3.710  21.642  1.00
>          1.60              N
>            ATOM     23 1HE2 GLN     3      18.031   3.421  21.665  1.00
>          0.80             HE
>            ATOM     24 2HE2 GLN     3      16.790   4.446  21.071  1.00
>          0.80             HE
>            ATOM     25  C   GLN     3      11.689   2.846  21.556  1.00
>          2.10              C
>            ATOM     26  O   GLN     3      11.395   3.988  21.389  1.00
>          1.60              O
>            ATOM     27  N   LEU     4      11.403   1.872  20.676  1.00
>          1.60              N
>            ATOM     28  H   LEU     4      11.747   0.959  20.767  1.00
>          0.80              H
>            ATOM     29  CA  LEU     4      10.606   2.121  19.473  1.00
>          2.37              C
>            ATOM     30  CB  LEU     4      11.011   1.111  18.398  1.00
>          2.23              C
>            ATOM     31  CG  LEU     4      12.501   1.073  18.020  1.00
>          2.37              C
>            ATOM     32  CD1 LEU     4      12.869  -0.185  17.207  1.00
>          2.17              C
>            ATOM     33  CD2 LEU     4      12.893   2.344  17.332  1.00
>          2.17              C
>            ATOM     34  C   LEU     4       9.082   2.102  19.484  1.00
>          2.10              C
>            ATOM     35  O   LEU     4       8.400   1.579  20.374  1.00
>          1.60              O
>            ATOM     36  N   CBX     5       8.609   2.722  18.430  1.00
>          1.60              N
>            ATOM     37  H   CBX     5       9.198   3.338  17.946  1.00
>          0.80              H
>            ATOM     38  CH3 CBX     5       7.176   2.594  17.895  1.00
>          2.17              C
>            ATOM     39 1HH3 CBX     5       6.785   1.605  18.135  1.00
>          2.17              H
>            ATOM     40 2HH3 CBX     5       7.178   2.732  16.814  1.00
>          2.17              H
>            ATOM     41 3HH3 CBX     5       6.547   3.355  18.357  1.00
>          2.17              H
>            TER
>            ENDMDL
> 
> 
>            These files were generated using the option -COOH for C terminal.
>            *However, if "none" is chosen, I get the error:*
> 
>            Fatal error:
>              There is a dangling bond at at least one of the terminal ends.
>              Select a proper terminal entry.
>              For more information and tips for troubleshooting, please
>         check the
>              GROMACS
>               I have used Mark's definitions for capping residues in the
>         rtp file.
> 
> 
>            Pooja
> 
> 
>            On Wed, Jul 7, 2010 at 4:47 PM, Justin A. Lemkul
>         <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>            <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
> 
> 
> 
>                Sai Pooja wrote:
> 
>                    I checked again and the error does not go. Please
>         read the
>                    steps below.
> 
>                    The pdb file I started off with did not have any
>         hydrogens.
>                    However, the way I had specified the capping residues
>         in the
>                    .rtp file (SEE MARK'S MAIL), I had to specify
>         hydrogens in
>                    the pdb file for the capping residues. So I used pymol to
>                    add hydrogens to my pdb file. I then used this file with
>                    charmm force field. However, pymol had added hydrogens
>                    everywhere and this was different from the definition
>         of the
>                    standard residues defined in the .rtp file. I could not
>                    directly use -ignh because I needed the hydrogens for the
>                    capping residues. So I created a file that contained the
>                    hydrogens on the capping residues only. This resolved the
>                    error related to hydrogens.
> 
> 
>                Probably an easier and more reliable approach would
>         simply be to
>                create an .hdb entry for your capping groups.
> 
> 
> 
>                    Error-from previous mail-NOT RESOLVED
>                    (Fatal error:
>                      There is a dangling bond at at least one of the
>         terminal ends.
>                      Select a proper terminal entry.
>                      For more information and tips for troubleshooting,
>         please
>                    check the
>                      GROMACS
>                       I have used Mark's definitions for capping residues in
>                    the rtp file.
> 
>                      In the pdb file, this is what the capping residues
>         look like:
> 
>                      ATOM     33  N   CBX     5       8.609   2.722  18.430
>                     1.00  1.60         FR1
>                      ATOM     34  H   CBX     5       9.198   3.338  17.946
>                     1.00  0.80         FR1
>                      ATOM     35 CH3  CBX     5       7.176   2.594  17.895
>                     1.00  2.17         FR1
> 
> 
>                Maybe this is just showing up incorrectly in my mail
>         client, but
>                I wonder if that CH3 is somehow misaligned and therefore not
>                correctly identified.  I presume that you changed the residue
>                name in the .rtp file accordingly?  I suppose the error
>         message
>                would be different (something like "residue not found") but I
>                just want to make sure.  Mark's entry used NAC.
> 
> 
>                      ATOM      1  CH3 ACE     1      12.782  -0.027  28.022
>                     1.00  2.17         FR1
>                      ATOM      2  C   ACE     1      12.532  -0.094  26.546
>                     1.00  2.10         FR1
>                      ATOM      3  O   ACE     1      13.443  -0.213  25.696
>                     1.00  1.60         FR1 )
> 
>                    The error stated in the previous mail(quoted above)
>         occurred
>                    when I chose "none" for the both terminals or the
>         carboxylic
>                    terminal option (using -ter). It worked fine if I chose
>                    "none" at the N terminal and any other option except
>         "none"
>                    at the carboxylic acid terminal. So I chose "none" at N
>                    terminal and some option randomly at the carboxylic acid
>                    terminal. As expected, it adds a terminal at that end
>         of the
>                    residue before my capping residue which is something
>         I DONT
>                    want. I
> 
> 
>                So does pdb2gmx somehow add the C-terminal cap after the
>                carboxylate terminus?
> 
> 
>                    havent been able to find a way around it. Interestingly,
>                    when I generate a pdb file using -q, and open that
>         pdb file
>                    in pymol, I dont get the terminal carboxylic acid that
>                    pdb2gmx gives in the .gro file.
> 
> 
>                So the cap is applied properly in that structure?
> 
> 
>                    I am not sure how to correct this. One way would be to
>                    remove those entries from the final .gro and .top
>         file but
>                    not sure if that would be right.
> 
> 
>                This all sounds very fishy.  This may be worth a bugzilla
>         entry,
>                but only if you can build the structure in a very sound way,
>                probably using .hdb entries (or an appropriate all-atom
>                structure, which you've yet to demonstrate).
> 
>                -Justin
> 
>                    Pooja
> 
> 
> 
> 
> 
> 
> 
>                    On Sat, Jul 3, 2010 at 4:41 PM, Justin A. Lemkul
>                    <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
> 
> 
> 
>                       Sai Pooja wrote:
> 
>                           Follow-up. It is easy to make it work. Just
>         needed to
>                    be more
>                           rigorous. Thank you.
> 
> 
>                       It would be helpful if you describe what you mean.
>          This
>                    error
>                       message is new to me, and appears to reflect new
>                    mechanics in the
>                       upcoming Gromacs release.  If you describe what the
>                    problem was, how
>                       you resolved it, what your pdb2gmx command line
>         was, and
>                    anything
>                       else that might be useful, that would likely help
>         others
>                    solve this
>                       issue in the future.
> 
>                       -Justin
> 
>                           On Fri, Jul 2, 2010 at 5:43 PM, Sai Pooja
>                    <saipooja at gmail.com <mailto:saipooja at gmail.com>
>         <mailto:saipooja at gmail.com <mailto:saipooja at gmail.com>>
>                           <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
> 
>                    <mailto:saipooja at gmail.com <mailto:saipooja at gmail.com>>
> 
>                           <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>>>> wrote:
> 
>                              I used -ter option and selected "none" for both
>                    terminal ends
>                           but I
>                              still get this error:
> 
>                              Fatal error:
>                              There is a dangling bond at at least one of the
>                    terminal ends.
>                              Select a proper terminal entry.
>                              For more information and tips for
>         troubleshooting,
>                    please
>                           check the
>                              GROMACS
>                               I have used Mark's definitions for capping
>                    residues in the
>                           rtp file.
> 
>                              In the pdb file, this is what the capping
>         residues
>                    look like:
> 
>                              ATOM     33  N   CBX     5       8.609   2.722
>                     18.430  1.00
>                            1.60         FR1
>                              ATOM     34  H   CBX     5       9.198   3.338
>                     17.946  1.00
>                            0.80         FR1
>                              ATOM     35 CH3  CBX     5       7.176   2.594
>                     17.895  1.00
>                            2.17         FR1
> 
>                              ATOM      1  CH3 ACE     1      12.782  -0.027
>                     28.022  1.00
>                            2.17         FR1
>                              ATOM      2  C   ACE     1      12.532  -0.094
>                     26.546  1.00
>                            2.10         FR1
>                              ATOM      3  O   ACE     1      13.443  -0.213
>                     25.696  1.00
>                            1.60         FR1
> 
> 
> 
> 
> 
> 
>                              On Fri, Jul 2, 2010 at 10:50 AM, Justin A.
>         Lemkul
>                           <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>
>                              <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu> <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu>>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>>> wrote:
> 
> 
> 
>                                  Sai Pooja wrote:
> 
>                                      Thanks Marks. I tried it but this
>         is what
>                    I get:
> 
>                                      Fatal error:
>                                      atom N not found in buiding block
>         1ACE while
>                           combining tdb
>                                      and rtp
>                                      For more information and tips for
>                    troubleshooting, please
>                                      check the GROMACS
>                                      website at
>                    http://www.gromacs.org/Documentation/Errors
> 
>                                      Do I need to edit the aminoacids.n.tdb
>                    file as well?
> 
> 
>                                  What are you choosing as your termini
>         when running
>                           pdb2gmx?  It
>                                  should be "none," since by capping, you are
>                    not choosing a
>                                  protonation state for the N- and C-termini.
> 
>                                  -Justin
> 
> 
>                                      Pooja
> 
> 
> 
>                                      On Thu, Jul 1, 2010 at 11:39 PM,
>         Mark Abraham
>                                      <mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>
>                           <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au> <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>
>                           <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>>>
>                                      <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>
>                           <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>>
>                                      <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>
>                           <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>
>                    <mailto:mark.abraham at anu.edu.au
>         <mailto:mark.abraham at anu.edu.au>>>>>> wrote:
> 
> 
> 
>                                         ----- Original Message -----
>                                         From: Sai Pooja
>         <saipooja at gmail.com <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com <mailto:saipooja at gmail.com>>
>                           <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>>
>                                      <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com <mailto:saipooja at gmail.com>>
>                           <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>>> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com <mailto:saipooja at gmail.com>>
>                           <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>>
>                                      <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>> <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>
>                    <mailto:saipooja at gmail.com
>         <mailto:saipooja at gmail.com>>>>>>
>                                         Date: Friday, July 2, 2010 7:28
>                                         Subject: Re: [gmx-users] Capping
>         residues
>                                         To: jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>
>                           <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu> <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu>>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>>
>                                      <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>
>                           <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu> <mailto:jalemkul at vt.edu
>         <mailto:jalemkul at vt.edu>>
>                    <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>>>,
>                                      Discussion list for
>                                         GROMACS users
>         <gmx-users at gromacs.org <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>
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>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>>
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>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>
>                           <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>>>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org> <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>
> 
>                           <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>>
> 
>                                      <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>
>                           <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>
>                    <mailto:gmx-users at gromacs.org
>         <mailto:gmx-users at gromacs.org>>>>>>
> 
>                                          > I am sorry if I did not frame the
>                    question
>                           correctly,
>                                      but putting
>                                         it very simply, is there a way
>         to use
>                    capping residues
>                                      with the
>                                         charmm forcefield if the
>         residues are
>                    --COCH3 and
>                           NHCH3?
> 
>                                         Yes - you edit a copy of the
>         .rtp file
>                    in your working
>                                      directory and
>                                         add whatever you want. Here's what I
>                    use in CHARMM
> 
>                                         [ ACE ]
>                                          [ atoms ]
>                                                 CH3     CT3     -0.270  0
>                                                 HH31    HA      0.090   0
>                                                 HH32    HA      0.090   0
>                                                 HH33    HA      0.090   0
>                                                 C       C       0.510   1
>                                                 O       O       -0.510  1
>                                          [ bonds ]
>                                                 C       CH3
>                                                 C       +N
>                                                 CH3     HH31
>                                                 CH3     HH32
>                                                 CH3     HH33
>                                                 O       C
>                                          [ impropers ]
>                                                 C       CH3     +N      O
> 
>                                         [ NAC ]
>                                          [ atoms ]
>                                                N       NH1     -0.470  1
>                                                HN      H       0.310   1
>                                                CH3     CT3     -0.110  1
>                                                HH31    HA      0.090   1
>                                                HH32    HA      0.090   1
>                                                HH33    HA      0.090   1
>                                          [ bonds ]
>                                                -C      N
>                                                N       HN
>                                                N       CH3
>                                                CH3     HH31
>                                                CH3     HH32
>                                                CH3     HH33
> 
>                                          [ impropers ]
>                                                N       -C      CH3     HN
>                                                -C      CH3     N       -O
> 
>                                         Mark
>                                         --
>                                         gmx-users mailing list          
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> 
>                                      --             Quaerendo
>         Invenietis-Seek
>                    and you
>                           shall discover.
> 
> 
>                                  --                  
>          ========================================
> 
>                                  Justin A. Lemkul
>                                  Ph.D. Candidate
>                                  ICTAS Doctoral Scholar
>                                  MILES-IGERT Trainee
>                                  Department of Biochemistry
>                                  Virginia Tech
>                                  Blacksburg, VA
>                                  jalemkul[at]vt.edu <http://vt.edu>
>         <http://vt.edu>
>                    <http://vt.edu> <http://vt.edu> |
> 
>                           (540) 231-9080
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>                                            
>         http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>                              --     Quaerendo Invenietis-Seek and you shall
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> 
> 
> 
> 
>                           --         Quaerendo Invenietis-Seek and you shall
>                    discover.
> 
> 
>                       --     ========================================
> 
>                       Justin A. Lemkul
>                       Ph.D. Candidate
>                       ICTAS Doctoral Scholar
>                       MILES-IGERT Trainee
>                       Department of Biochemistry
>                       Virginia Tech
>                       Blacksburg, VA
>                       jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>         <http://vt.edu> |
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>                    --             Quaerendo Invenietis-Seek and you
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> 
> 
>                --         ========================================
> 
>                Justin A. Lemkul
>                Ph.D. Candidate
>                ICTAS Doctoral Scholar
>                MILES-IGERT Trainee
>                Department of Biochemistry
>                Virginia Tech
>                Blacksburg, VA
>                jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> |
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> 
> 
>         -- 
>         Quaerendo Invenietis-Seek and you shall discover.
> 
> 
>     -- 
>     ========================================
> 
>     Justin A. Lemkul
>     Ph.D. Candidate
>     ICTAS Doctoral Scholar
>     MILES-IGERT Trainee
>     Department of Biochemistry
>     Virginia Tech
>     Blacksburg, VA
>     jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
>     http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
>     ========================================
>     -- 
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> 
> 
> 
> 
> -- 
> Quaerendo Invenietis-Seek and you shall discover.

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

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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



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