[gmx-users] About topology for cyclic petide

[vidhya sankar]

Dear justin 

                Thank you for your Previous reply
I Have Successfully constructed topology for cyclic peptide  using spce bond and Other Appropriate Changes in the . top files 

Yet I Want to make CO Terminal  But When I interactively Choose the Terminal  By pdb2gmx  It Shows Only 

1)COO -
2)COOH
3)None 

I want to Make One more Choice Namely CO For C-Terminal Residue of (LAst Residue ) My Cyclic Peptide 

It Adds One Two oxygen atom on the Carbon Atom (O1 & O2) . But I Need the Addition Of One Oxygen Atom
How to Do It ?
 Which Database file  Should I EDIT ? .C Terminal Data Base

Thanks In Advance