All,

I need to refine a ligand that consists of two stereoisomers in my active site.  I have decent density and have created models for the r and s forms of the guest with separate cif files.  They have been fit independently into the active site density.  My questions are;

How to show these in the pdb file.  Separate chains?  Separate amino acids in a given chain?

How do I keep them from interacting with one another during refinement?

Creating an alt-position seems obvious but I'm not certain how to apply the different stereo restraints in that case.

I'm sure someone has solved this before but I can't seem to find that information. 

Thanks,

Nic Steussy

Purdue University.