PDBs are great, however from time to time you only actually want one protein chain to analyse at a time. What you need to do then is split the PDB of many chains into separate PDB files.
This MATLAB script does exactly that. Using local .pdb files (selectable via an open window) or files directly from rcsb.org (using PDB identifier code) up to 4 chains (in this current version) are exported to the current work folder.
This script does use pdbread and pdbwrite from the Mathworks Bioinformatics Toolbox. This is not the ideal open source script I wish it could be, but this is largely due to the widely varying PDB format.
I intend to look over how Jescke and Polyhach solve this problem in MMM and perhaps update this script at a later date.