[gmx-users] Adding modified nucleotide to a forcefield

william Stebbeds willstebbeds at hotmail.com
Fri Feb 4 04:42:27 CET 2011


Thanks again, 

You were right, it was a misaligned pdb file :).

However I now get an error when I use grompp:

ERROR 1 [file newoxi.noNaCl_DNA.itp, line 1381]:
  No default Bond types


ERROR 2 [file newoxi.noNaCl_DNA.itp, line 4462]:
  No default Angle types


ERROR 3 [file newoxi.noNaCl_DNA.itp, line 4464]:
  No default Angle types


ERROR 4 [file newoxi.noNaCl_DNA.itp, line 6919]:
  No default Improper Dih. types

My assumption is that I have not set the angles and dihedrals properly but have rechecked the rtp entry and all seems to be correct.

Once Again thank you for helping out a gromacs newbie.



> Date: Thu, 3 Feb 2011 20:43:24 -0500
> From: jalemkul at vt.edu
> To: gmx-users at gromacs.org
> Subject: Re: [gmx-users] Adding modified nucleotide to a forcefield
> 
> 
> 
> william Stebbeds wrote:
> > Thanks for the reply,
> > 
> > ffamber99sb.rtp entry:
> > [ DGO ]
> >  [ atoms ]
> >      P    amber99_46    1.16590     1
> >    O1P    amber99_45   -0.77610     2
> >    O2P    amber99_45   -0.77610     3
> >    O5'    amber99_44   -0.49540     4
> >    C5'    amber99_11   -0.00690     5
> >   H5'1    amber99_19    0.07540     6
> >   H5'2    amber99_19    0.07540     7
> >    C4'    amber99_11    0.16290     8
> >    H4'    amber99_19    0.11760     9
> >    O4'    amber99_44   -0.36910    10
> >    C1'    amber99_11    0.03580    11
> >    H1'    amber99_20    0.17460    12
> >     N9    amber99_40    0.05770    13
> >     C8    amber99_6     0.07360    14
> >     O8    amber99_44   -0.36910    15
> >     N7    amber99_36   -0.57250    16
> >     C5    amber99_4     0.19910    17
> >     C6    amber99_2     0.49180    18
> >     O6    amber99_41   -0.56990    19
> >     N1    amber99_35   -0.50530    20
> >     H1    amber99_17    0.35200    21
> >     C2    amber99_3     0.74320    22
> >     N2    amber99_38   -0.92300    23
> >    H21    amber99_17    0.42350    24
> >    H22    amber99_17    0.42350    25
> >     N3    amber99_37   -0.66360    26
> >     C4    amber99_4     0.18140    27
> >    C3'    amber99_11    0.07130    28
> >    H3'    amber99_19    0.09850    29
> >    C2'    amber99_11   -0.08540    30
> >   H2'1    amber99_18    0.07180    31
> >   H2'2    amber99_18    0.07180    32
> >    O3'    amber99_44   -0.52320    33
> >   [ bonds ]
> >      P   O1P
> >      P   O2P
> >      P   O5'
> >    O5'   C5'
> >    C5'  H5'1
> >    C5'  H5'2
> >    C5'   C4'
> >    C4'   H4'
> >    C4'   O4'
> >    C4'   C3'
> >    O4'   C1'
> >    C1'   H1'
> >    C1'    N9
> >    C1'   C2'
> >     N9    C8
> >     N9    C4
> >     C8    O8
> >     C8    N7
> >     N7    C5
> >     C5    C6
> >     C5    C4
> >     C6    O6
> >     C6    N1
> >     N1    H1
> >     N1    C2
> >     C2    N2
> >     C2    N3
> >     N2   H21
> >     N2   H22
> >     N3    C4
> >    C3'   H3'
> >    C3'   C2'
> >    C3'   O3'
> >    C2'  H2'1
> >    C2'  H2'2
> >   -O3'     P
> >  [ dihedrals ]
> >    O4' C1' N9 C4   proper_X_CT_N*_X
> >    C1' N9  C8 O8   proper_X_CK_N*_X
> >    C1' N9  C8 N7   proper_X_CK_N*_X
> >    C1' N9  C4 C5   proper_X_CB_N*_X
> >    C1' N9  C4 N3   proper_X_CB_N*_X
> >    H1' C1' N9 C8   proper_X_CT_N*_X
> >    H1' C1' N9 C4   proper_X_CT_N*_X
> >    C8  N9  C4 C5   proper_X_CB_N*_X
> >    C8  N9  C4 N3   proper_X_CB_N*_X
> >    C5  C6  N1 H1   proper_X_C_NA_X
> >    C5  C6  N1 C2   proper_X_C_NA_X
> >    C6  N1  C2 N2   proper_X_CA_NA_X
> >    C6  N1  C2 N3   proper_X_CA_NA_X
> >    O6  C6  N1 H1   proper_X_C_NA_X
> >    O6  C6  N1 C2   proper_X_C_NA_X
> >    N1  C2  N3 C4   proper_X_CA_NC_X
> >    H1  N1  C2 N2   proper_X_CA_NA_X
> >    H1  N1  C2 N3   proper_X_CA_NA_X
> >    N2  C2  N3 C4   proper_X_CA_NC_X
> >    H8  C8  N7 C5   proper_X_CK_NB_X
> >    N9  C8  N7 C5   proper_X_CK_NB_X
> >    H8  C8  N9 C4   proper_X_CK_N*_X
> >    N7  C8  N9 C4   proper_X_CK_N*_X
> >    O4' C1' C2' H2'1   proper_H_CT_CT_O
> >    O4' C1' C2' H2'2   proper_H_CT_CT_O
> >    O3' C3' C2' H2'1   proper_H_CT_CT_O
> >    O3' C3' C2' H2'2   proper_H_CT_CT_O
> >  [ impropers ]
> >     C4    C8    N9   C1'  nucleic_imp_10
> >     C5    N1    C6    O6
> >     C6    C2    N1    H1  nucleic_imp_10
> >     C2   H21    N2   H22
> >     N9    N7    C8    O8
> >     N2    N1    C2    N3  nucleic_imp_11
> > 
> > DGO was also added to residuetypes.dat. hdb file was also updated, as 
> > was dna.rtp within amber99sb.ff.
> > 
> > The problem is not a simple missing bond, as when the structure goes 
> > through pdb2gmx, the new nucleotide appears on the other side of the 
> > pbc, in a straight line (i.e. without form).
> > 
> 
> As in, the atoms of DGO are visually a straight line?  That would be a 
> consequence of an incorrectly-formatted input file.  If you're using a .pdb 
> file, it's fixed-format, so any incorrect spacing will screw up the coordinates.
> 
> To clarify, are you missing a bond, as your first message would imply?  I can 
> see how you might be missing bonds; your residue definition doesn't specify a 
> bond to the next nucleotide (i.e. "O3' +P"), although if it's a 3' ending 
> nucleotide, this wouldn't apply.  If it's an internal residue, you may also be 
> missing necessary dihedral definitions as well.
> 
> -Justin
> 
> > Thanks
> > 
> > Will
> > 
> >  > Date: Thu, 3 Feb 2011 16:07:42 -0500
> >  > From: jalemkul at vt.edu
> >  > To: gmx-users at gromacs.org
> >  > Subject: Re: [gmx-users] Adding modified nucleotide to a forcefield
> >  >
> >  >
> >  >
> >  > william Stebbeds wrote:
> >  > > Hello,
> >  > >
> >  > > I am attempting to add 8-oxo-dG (8-Oxo-2'-deoxyguanosine) to the
> >  > > amber99sb force field. This is a simple modification of the H8 
> > hydrogen
> >  > > on a guanine to an oxygen atom. I have followed the instructions on 
> > the
> >  > > gromacs site on adding residues.
> >  > >
> >  > > However the new nucleotide will not work, it will not attach to the
> >  > > adjacent nucleotides in the sequence.
> >  > >
> >  >
> >  > So a bond is missing?
> >  >
> >  > > Any help would be very much appreciated, if any more information is
> >  > > required please let me know.
> >  > >
> >  >
> >  > A lot more information is needed, at the very least, your .rtp entry.
> >  >
> >  > -Justin
> >  >
> >  > > Best Regards
> >  > >
> >  > > William Stebbeds
> >  > > Cranfield University
> >  > > UK
> >  > >
> >  >
> >  > --
> >  > ========================================
> >  >
> >  > 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
> >  >
> >  > ========================================
> >  > --
> >  > gmx-users mailing list gmx-users at gromacs.org
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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 | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
> ========================================
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