Hi Lauriane,
Coordinate import will not work, unless your three-letter code corresponds to a compound already in the PDB, you can search via:
http://www.ebi.ac.uk/pdbe-srv/pdbechem/
ERA, in this case, is mostly hydrocarbon chain.
It's the chemComp import that should work - send me the file and I'll have a look.
Wim
|