[gmx-users] Atom O5 not found in residue seq.nr. 1 while adding atom

[pragna lakshmi]

Dear Gromacs Users,
                I need to simulate a protein that has N-acetyl glucosamine
(NAG). Since NAG residue is not present in residue topology file, first of
all i added NAG parameters to aminoacids.rtp file. I am following this link
*
http://www.gromacs.org/Documentation/How-tos/Adding_a_Residue_to_a_Force_Field
*

This is my aminoacids.rtp file for NAG.

[ NAG ] ; N-Acetylglucosamine

[ atoms ]
   C1    opls_195   +0.365    1
  HC1    opls_196   +0.100    1
   O1    opls_187   -0.700    1
  HO1    opls_188   +0.435    1
   C5    opls_183   +0.170    1
  HC5    opls_185   +0.030    1
   O5    opls_180   -0.400    1
   C2    opls_229   +0.140    2
  HC2    opls_140   +0.060    2
   N2    opls_238   -0.500    2
  N15    opls_238   -0.500    2
  HN2    opls_241   +0.300    2
   C3    opls_158   +0.205    3
  HC3    opls_140   +0.060    3
   O3    opls_154   -0.683    3
  O3H    opls_155   +0.418    3
  O2H    opls_155   +0.418    3
   C4    opls_158   +0.205    4
  HC4    opls_140   +0.060    4
   O4    opls_154   -0.683    4
   OM    opls_154   -0.683    4
  O4H    opls_155   +0.418    4
   C6    opls_157   +0.145    5
HC61    opls_140   +0.060    5
HC62    opls_140   +0.060    5
   O6    opls_154   -0.683    5
  O6H    opls_155   +0.418    5
   C7    opls_235   +0.500    6
   O7    opls_236   -0.500    6
   C8    opls_135   -0.180    7
HC81    opls_140   +0.060    7
HC82    opls_140   +0.060    7
HC83    opls_140   +0.060    7
  OR    opls_154   -0.683    5
  OW    opls_154   -0.683    5

[ bonds ]
   C1  HC1
   C1   O1
   C1   C2
   C1   O5
   O1  HO1
   C2  HC2
   C2   N2
   C2   C3
   N2  HN2
   N2   C7
   C3  HC3
   C3   O3
   C3   C4
   O3  HO3
   C4  HC4
   C4   O4
   C4   C5
   O4  HO4
   C5  HC5
   C5   O5
   C5   C6
   C6 HC61
   C6 HC62
   C6   O6
   O6  HO6
   C7   O7
   C7   C8
   C8 HC81
   C8 HC82
   C8 HC83

Now i have got this error.

Fatal error:
Atom O5 not found in residue seq.nr. 1 while adding atom

If any body knows solution for this, can you please reply this. If any
error is there in aminoacids.rtp file, please mention it. I will change it
accordingly. Any suggestion is appreciable.
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