Questions and problems?

Sulfur parameters

Where can I obtain sulfur-related parameters? The following is a list (actually a sampling of a) list of missing parameters detected by Parm:
 

    Missing bond parameter: SH-SH     (atoms    52-  566)
    Missing bond parameter: SH-SH     (atoms   130-  376)
    Missing bond parameter: SH-SH     (atoms   301-  519)

    Missing angle parameter: C2-SH-SH (atoms    51-   52-  566)
    Missing angle parameter: HS-SH-SH (atoms    53-   52-  566)
    Missing angle parameter: LP-SH-SH (atoms    55-   52-  566)
    Missing dihedral parameter: C2-SH-SH-LP (atoms    51-   52-  566-  569)
    Missing dihedral parameter: HS-SH-SH-C2 (atoms    53-   52-  566-  565)
The real problem in this case is neglecting to replace CYS with the disulfide residue CYX and then trying to attach SH with SH, which there are no parameters for.