[gmx-users] AA not present in the ffG43a1.rtp

[Mattia Sturlese]

Dear all,
     I have a protein with an oxidated Cys( to sulfinic acid) , this 
residue is not present in the residue database. I use PRODGR to obtain 
the .itp file of  the residue but I don't start grompp ....

How I insert this residue in the rtp file?? I trying  insert the 
parameters manually but I have explicit data of angles, bond, dihedral 
and impropers....but ffG43a use Gromos Type definition as ga_XX or 
gb_XX......  Where i find a database of this gromos type? Or How I can 
insert my .itp file ?

Thanks folk!!
Mattia Sturlese