26 January 2012, 16:15
Ernst-Abbe-Platz 2, seminar room 3423

Identifying the unknowns: Automated interpretation of mass spectra from small molecules

Prof. Dr. Sebastian Böcker (Chair of Bioinformatics, FSU Jena)The structural elucidation of organic compounds in complex biofluids and tissues remains a significant analytical challenge. For mass spectrometry, the manual interpretation of fragmentation mass spectra is cumbersome and requires expert-knowledge. The automated identification of compounds is generally limited to searching databases in spectral libraries. Practically no computational methods are known for “identifying the unknowns” that are not in any database.

I present a fully automated method for interpreting these tandem mass spectra. In the first step, a fragmentation tree is computed that establishes not only the molecular formula of the compound and all fragment ions, but also the dependencies between fragment ions. This methods works both for LC/MS and GC/MS data with high mass accuracy. In the second step, compound similarity is established by an automated comparison of such trees. I present first results for clustering unknown compounds and establishing their chemical similarity. The method has successfully been evaluated on five datasets from five different labs.