Dear all, I am trying to solve the structure of a peptide with C-terminal amide. In order to add the amide group to the c-terminal TYR, I substituted TYR with TYC (tyrosinamide) and created a link between the preceding GLY and TYC. When refined in refmac, the pdb inserts a TER card between GLY and TYC and no covalent bond is created between them. How do I fix this? I have also tried to add NH2 pointer atom to TYR in coot and create a link between them but in vain. I also imported the NH2.cif file into coot and tried to make a link but of no use. I also tried to import NH2.cif into Jligand so I could get a link record but it refuses to open the NH2.cif file.
I would greatly appreciate any help! Best regards, Abhishek