Normally a contact is defined between two residues if they have at least
one pair of atoms that touch. For contact prediction purposes one normally
uses a C-alpha - C-alpha distance less than typically 10 Angstrom. Contact
me if you need a server with a different distance.
If you have detected any error, or have any question or suggestion,
please send an Email to Gert Vriend.
Roland Krause, Maarten L Hekkelman, Jens E Nielsen,