I am doing packing on PDB ID 1UKU and looking at two solutions my code produces, one having much higher energy than the other. The only difference between them is that the conformation of one of the Tryptophan residues is different, the other 100 or so residues are unchanged.
Visualizing the result in PyMol it looks like the higher energy configuration is interacting with a nearby Glutamic Acid residue. I've attached an image showing just these two residues (Res95 Trp and Res99 Glu). The image shows the two conformations for Trp, one which is interacting with Glu and has higher energy.
Because my chemistry background is poor, I'm wondering if someone could briefly tell me specifically what type of interaction is happening here. And in particular, in Rosetta what energy term would be evaluating this interaction?