PDB2PQR is a Python software package that automates many of the common tasks of preparing structures for continuum electrostatics calculations. It thus provides a platform-independent utility for converting protein files in PDB format to PQR format. These tasks include: * Adding a limited number of missing heavy atoms to biomolecular structures * Determining side-chain pKas * Placing missing hydrogens * Optimizing the protein for favorable hydrogen bonding * Assigning charge and radius parameters from a variety of force fields

This package also includes PropKa, a tool to modify the protonation state of protein structures in the Protein Data Bank (PDB) format to match a given pKa value. It can also be used to refine NMR structures, which often yield inaccurate pKa values for some residues.