If you molecule and electrostatic potential map align when they are the only two data sets you open in Chimera, but they don’t align when you have other opened data sets, I suspect you’ve run into the falling pitfall. When you open a molecule or map in Chimera it positions it using the coordinate system of the currently opened data with lowest model id number. This won’t matter if all the currently open models have the same coordinate system. But if you have moved one of those currently opened models relative to the others then they have different coordinate systems. To get your molecule and map misaligned you might open a few molecules, move the one with lowest id number relative to the others, then open your potential map which lets say is supposed to align with molecule #2. The map won’t align with that molecule, instead it will align with the lowest id model that you moved. To fix this if your opened map has model id number 3 you could use the Chimera command “matrixcopy #2 #3” to set the coordinate system of the map to match the coordinate system of molecule with id #2.
From: Joshua Broyde
Subject: Re: [Chimera-users] Delphi electrostatic potential visualization
Date: August 4, 2014 at 9:41:19 AM PDT
To: Tom Goddard
Tom,
This theory was correct. Thanks for the help. However, I notice that chimera only recognizes the surface as lying outside of the Delphi map if the model is not the only one in the Chimera session. So if I take the exact same model and open a new session with just that PDB and I map the electrostatics onto the surface, the electrostatics displays correctly. Any ideas why this could be?
Thanks!
Josh