CHARMM Development Project Forums User Discussion & Questions Parameter Set Discussion All possible torsions?

Hi

Could somebody please give some clarification on how charmm deals with possible torsion angles (and associated degrees of freedom?). That is, are all possible torsions explicitely represented?.
I am trying to parameterise a ligand based on existing paramater entries, but, for example, I don't find any dihedrals (all27_prot_na) with a terminal "S" atom type. However, such torsions exist in methionine.

Thanks
Gordon Wells

Hi Gordon,

The X atom type is a wildcard and matches any atom type, so dihedral terms with a sulfur at the end would be covered by definitions like X C C X (if there are no S-specific terms).