[gmx-users] forcefield to handle phosphorylated residues (ffG43a1p)

[Una Bjarnadottir]

Dear all,

I have just started to use GROMACS for MD's and have downloaded the 
forcefield to handle phosphorylated residues (*ffG43a1p)*.  But I keep 
getting the error when I run pdb2gmx and select the forcefield that it 
does not recognize the phosphoryl group or the oxygen atoms in the 
phosphoryl group.

Fatal error: Atom PD/P in residue TPO 183 not found in rtp entry with 12 
atoms while sorting atoms
Fatal error: Atom OE1/O1 in residue TPO 183 not found in rtp entry with 
12 atoms while sorting atoms

How should I tread the residuses which are phosphorylated and how to 
treat the phosphorylgroup itself? 
I have put the phosphoryl group both with the residue,  copy it from the 
end of the pdb file and add it to the residues which are phosphorylated 
and kept it last?  Do I call the whole residue TPO for phosphorylated 
threonine or only the phosphorylgroup, or call the phosphoryl group PHO 
and the residue TPO itself, also I have added the P-group to the residue 
and called it I have tryed all kinds of things but nothing seems to 
work.  I have searched for help but have not found anything for this 
"silly" problem.


I would really appreciate it if somebody will bother helping me!

Best regards, Una