Dear Chimerax Developers, There is a debate in my lab about the best way to compare two PDBs of the same protein bound to different ligands; the goal is to identify subtle differences in the binding pocket between the ligand-bound conditions. One method of comparison is to fit the two density maps together using the FitMap function, and then fit each PDB into their respective maps which have been aligned. Another way is to simply align the two PDBs (such as the align function in Pymol). Using these two methods results in slightly different alignments of the PDBs and thus give slightly different positional differences of the binding pocket and ligands. The resolution of these density maps range from 2.4 - 3.5 angstroms. Which way would be the more accurate way to look at the differences between two similar models? Thank you! Sincerely, -- Kevin C. Felt PhD Candidate - Chakrapani Lab Department of Physiology and Biophysics School of Medicine Case Western Reserve University