[gmx-users] How to cap a single residue in gromacs (Alessandra Villa)

Sadaf Rani sadafrani6 at gmail.com
Wed Feb 19 12:29:36 CET 2020


Thank you, Alessandra, for your reply.
I have tried TER in the PDB file but it doesn't work. It requires an N and
C terminal for amino acid residue. I have prepared residue in avogadros and
used these coordinates.
ATOM      1  N   PHE A   1       0.000   0.000   0.000  1.00  0.00
  N1+
ATOM      2  CA  PHE A   1       1.462   0.000   0.000  1.00  0.00
  C
ATOM      3  C   PHE A   1       1.902   0.000   1.473  1.00  0.00
  C
ATOM      4  O   PHE A   1       1.105   0.000   2.411  1.00  0.00
  O
ATOM      5  CB  PHE A   1       2.020   1.225  -0.743  1.00  0.00
  C
ATOM      6  CG  PHE A   1       3.442   1.037  -1.219  1.00  0.00
  C
ATOM      7  CD2 PHE A   1       4.512   1.642  -0.547  1.00  0.00
  C
ATOM      8  CE2 PHE A   1       5.823   1.440  -0.982  1.00  0.00
  C
ATOM      9  CZ  PHE A   1       6.074   0.642  -2.097  1.00  0.00
  C
ATOM     10  CE1 PHE A   1       5.015   0.044  -2.777  1.00  0.00
  C
ATOM     11  CD1 PHE A   1       3.705   0.238  -2.340  1.00  0.00
  C
ATOM     12  H   PHE A   1      -0.467   0.280   0.859  1.00  0.00
  H
ATOM     13  HA  PHE A   1       1.790  -0.939  -0.463  1.00  0.00
  H
ATOM     14  HB1 PHE A   1       1.956   2.118  -0.106  1.00  0.00
  H
ATOM     15  HB2 PHE A   1       1.405   1.454  -1.623  1.00  0.00
  H
ATOM     16  HD2 PHE A   1       4.334   2.273   0.322  1.00  0.00
  H
ATOM     17  HE2 PHE A   1       6.649   1.912  -0.456  1.00  0.00
  H
ATOM     18  HZ  PHE A   1       7.094   0.492  -2.441  1.00  0.00
  H
ATOM     19  HE1 PHE A   1       5.208  -0.570  -3.654  1.00  0.00
  H
ATOM     20  HD1 PHE A   1       2.885  -0.231  -2.885  1.00  0.00
  H
ATOM     21  HN  PHE A   1      -0.339   0.853  -0.435  1.00  0.00
  H
ATOM     22  2HN PHE A   1      -0.339  -0.853  -0.435  1.00  0.00
  H
ATOM     23  OXT PHE A   1       3.231  -0.000   1.717  1.00  0.00
  O1-

However, it claims that in the chosen force field there is no residue type
for 'PHE' as a standalone
(starting & ending) residue
I am using AMBER99SB-ILDN force field for protein.
I have looked into the force field both CPHE and NPHE are different as
below:-


[ CPHE ]
 [ atoms ]
     N    N           -0.38210     1
     H    H            0.26810     2
    CA    CT          -0.18250     3
    HA    H1           0.10980     4
    CB    CT          -0.09590     5
   HB1    HC           0.04430     6
   HB2    HC           0.04430     7
    CG    CA           0.05520     8
   CD1    CA          -0.13000     9
   HD1    HA           0.14080    10
   CE1    CA          -0.18470    11
   HE1    HA           0.14610    12
    CZ    CA          -0.09440    13
    HZ    HA           0.12800    14
   CE2    CA          -0.18470    15
   HE2    HA           0.14610    16
   CD2    CA          -0.13000    17
   HD2    HA           0.14080    18
     C    C            0.76600    19
   OC1    O2          -0.80260    20
   OC2    O2          -0.80260    21
 [ bonds ]
     N     H
     N    CA
    CA    HA
    CA    CB
    CA     C
    CB   HB1
    CB   HB2
    CB    CG
    CG   CD1
    CG   CD2
   CD1   HD1
   CD1   CE1
   CE1   HE1
   CE1    CZ
    CZ    HZ
    CZ   CE2
   CE2   HE2
   CE2   CD2
   CD2   HD2
     C   OC1
     C   OC2
    -C     N
 [ impropers ]
    -C    CA     N     H
    CA   OC1     C   OC2
    CG   CE2   CD2   HD2
    CZ   CD2   CE2   HE2
   CE1   CE2    CZ    HZ
   CD1    CZ   CE1   HE1
    CG   CE1   CD1   HD1
   CD1   CD2    CG    CB

[ NPHE ]
 [ atoms ]
     N    N3           0.17370     1
    H1    H            0.19210     2
    H2    H            0.19210     3
    H3    H            0.19210     4
    CA    CT           0.07330     5
    HA    HP           0.10410     6
    CB    CT           0.03300     7
   HB1    HC           0.01040     8
   HB2    HC           0.01040     9
    CG    CA           0.00310    10
   CD1    CA          -0.13920    11
   HD1    HA           0.13740    12
   CE1    CA          -0.16020    13
   HE1    HA           0.14330    14
    CZ    CA          -0.12080    15
    HZ    HA           0.13290    16
   CE2    CA          -0.16030    17
   HE2    HA           0.14330    18
   CD2    CA          -0.13910    19
   HD2    HA           0.13740    20
     C    C            0.61230    21
     O    O           -0.57130    22
 [ bonds ]
     N    H1
     N    H2
     N    H3
     N    CA
    CA    HA
    CA    CB
    CA     C
    CB   HB1
    CB   HB2
    CB    CG
    CG   CD1
    CG   CD2
   CD1   HD1
   CD1   CE1
   CE1   HE1
   CE1    CZ
    CZ    HZ
    CZ   CE2
   CE2   HE2
   CE2   CD2
   CD2   HD2
     C     O
     C    +N
 [ impropers ]
    CA    +N     C     O
    CG   CE2   CD2   HD2
    CZ   CD2   CE2   HE2
   CE1   CE2    CZ    HZ
   CD1    CZ   CE1   HE1
    CG   CE1   CD1   HD1
   CD1   CD2    CG    CB

How should I build it.

Thanks.

Sadaf


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