Probably the easiest way to mutate a residue is to use the `pyrosetta.toolbox.mutate_residue()` function. That should work if you just want a simple change of residue identity (to one of the standard 20 amino acids) and aren’t two picky about it.
For a little more control, you’ll want to read up on resfiles, the packer, and repacking/design.
If you’re doing something with residues that aren’t part of the the normal 20 amino acids, then the packer approach may work, but you might need to do other things, depending on what you’re interested in accomplishing.
I will admit, though, that I’m not quite sure what you’re looking for, or what “PFB forma” means. Perhaps if you expand upon what you’re attempting to accomplish, I might be able to give more specific suggestions.
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