[gmx-users] Topology file error for a ligand

Anirban Ghosh reach.anirban.ghosh at gmail.com
Mon Nov 23 10:46:20 CET 2009


Hi ALL,

I want to do a simulation of a protein in presence of a ligand (L-DOPA). I
am trying to obtain the topology of L-DOPA from the PRODRG server. However I
am getting an error in the number of atoms in the PDB file (with all
hydrogens) and the topology parameter file. The PDB file consists of 25
atoms, but the itp file gives definition for 22 atoms (3 hydrogens are
missing). So every time there is an error w.r.t. number of atoms mismatch.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
PDB:

TITLE     Gnomes, ROck Monsters And Chili Sauce
MODEL        1
ATOM      1  N   DAH     1      15.600  17.820  -3.200  1.00  0.00
ATOM      2  CA  DAH     1      16.490  17.500  -2.040  1.00  0.00
ATOM      3  C   DAH     1      18.010  17.580  -2.400  1.00  0.00
ATOM      4  O   DAH     1      18.560  16.790  -3.210  1.00  0.00
ATOM      5  CB  DAH     1      16.100  16.180  -1.290  1.00  0.00
ATOM      6  CG  DAH     1      14.980  16.190  -0.220  1.00  0.00
ATOM      7  CD1 DAH     1      13.790  16.990  -0.410  1.00  0.00
ATOM      8  CD2 DAH     1      15.130  15.410   0.970  1.00  0.00
ATOM      9  CE1 DAH     1      12.770  16.990   0.570  1.00  0.00
ATOM     10  CE2 DAH     1      14.100  15.400   1.950  1.00  0.00
ATOM     11  CZ  DAH     1      12.900  16.200   1.750  1.00  0.00
ATOM     12  OE2 DAH     1      14.280  14.630   3.070  1.00  0.00
ATOM     13  OZ  DAH     1      11.880  16.230   2.690  1.00  0.00
ATOM     14  OXT DAH     1      18.680  18.630  -1.760  1.00  0.00
ATOM     15  HA  DAH     1      16.330  18.300  -1.320  1.00  0.00
ATOM     16  HB2 DAH     1      15.790  15.470  -2.050  1.00  0.00
ATOM     17  HB3 DAH     1      17.000  15.790  -0.820  1.00  0.00
ATOM     18  HD2 DAH     1      16.020  14.820   1.110  1.00  0.00
ATOM     19  HE1 DAH     1      11.880  17.580   0.420  1.00  0.00
ATOM     20  HD1 DAH     1      13.670  17.590  -1.300  1.00  0.00
ATOM     21  HE2 DAH     1      15.190  14.330   3.110  1.00  0.00
ATOM     22  HZ  DAH     1      11.550  15.340   2.820  1.00  0.00
ATOM     23  H1  DAH     1      15.920  18.680  -3.630  1.00  0.00
ATOM     24  H2  DAH     1      15.640  17.070  -3.880  1.00  0.00
ATOM     25  H3  DAH     1      14.650  17.930  -2.880  1.00  0.00
TER
ENDMDL

TOPOLOGY FILE:

[ moleculetype ]
; Name nrexcl
DAH      3

[ atoms ]
;   nr      type  resnr resid  atom  cgnr   charge     mass
     1        OM     1  DAH       O     1   -0.715  15.9994
     2         C     1  DAH       C     1    0.387  12.0110
     3        OM     1  DAH     OXT     1   -0.716  15.9994
     4       CH1     1  DAH      CA     1    0.178  13.0190
     5        NL     1  DAH       N     1    0.683  14.0067
     6         H     1  DAH      H2     1    0.010   1.0080
     7         H     1  DAH      H3     1    0.010   1.0080
     8         H     1  DAH      H1     1    0.011   1.0080
     9       CH2     1  DAH      CB     1    0.152  14.0270
    10         C     1  DAH      CG     2   -0.020  12.0110
    11       CR1     1  DAH     CD2     2    0.001  12.0110
    12        HC     1  DAH     HD2     2    0.019   1.0080
    13         C     1  DAH     CE2     3    0.130  12.0110
    14        OA     1  DAH     OE2     3   -0.197  15.9994
    15         H     1  DAH     HE2     3    0.051   1.0080
    16         C     1  DAH      CZ     3    0.130  12.0110
    17        OA     1  DAH      OZ     3   -0.197  15.9994
    18         H     1  DAH      HZ     3    0.051   1.0080
    19       CR1     1  DAH     CE1     3    0.001  12.0110
    20        HC     1  DAH     HE1     3    0.031   1.0080
    21       CR1     1  DAH     CD1     4    0.000  12.0110
    22        HC     1  DAH     HD1     4    0.000   1.0080

[ bonds ]...
-----------------------------------------------------------------------------------------------------------------------------------------------------------
How can I rectify this issue? Any suggestion is welcome. Thanks a lot.

Regards,

Anirban
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