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About Unimod

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 MariaDB and the user interface was developed using PHPRunner 3.1