I have a protein complex that contains cytochromes, and so I need to type the atoms in the heme ring. Whilst I could get DS 2.1 to automatically type it, it assigned the atom types by analogy, even though there is a toppar_all22_prot_heme.str stream file available for hemes.

How do I get DS to recognise the heme ring as such, and call the stream file for atom typing?

Thanks!