Unimod is a public domain database, distributed under a copyleft
licence: "a copyright notice that permits unrestricted redistribution and modification, provided that
all copies and derivatives retain the same permissions."
The aim is to create a community supported, comprehensive database of protein modifications for mass
spectrometry applications. That is,
accurate and verifiable values, derived from elemental compositions, for the mass differences introduced by all types of
natural and artificial modifications. Other important information includes any mass change, (neutral loss), that occurs
during MS/MS analysis, and site specificity, (which residues are susceptible to modification and any constraints on
the position of the modification within the protein or peptide).
The goal is not to place this information in a biological context. There are already many high quality
sources of biological information about post-translational modifications:
Other compilations of modifications with a mass spectrometry bias:
Thanks to Achim Treumann and Saskia Severin of The Royal College Of Surgeons in Ireland for curation work.
On the Unimod public web site, the database engine is MySQL and the
user interface was developed using PHPRunner 3.1