Pyteomics is a collection of lightweight and handy tools for Python
that help to handle various sorts of proteomics data.  Pyteomics
provides a growing set of modules to facilitate the most common
tasks in proteomics data analysis, such as:

 * calculation of basic physico-chemical properties of polypeptides:
   . mass and isotopic distribution
   . charge and pI
   . chromatographic retention time
 * access to common proteomics data:
   . MS or LC-MS data
   . FASTA databases
   . search engines output
 * easy manipulation of sequences of modified peptides and proteins

WWW: https://pypi.python.org/pypi/pyteomics