University of Newcastle upon Tyne

School of Mathematics and Statistics

Statistics Seminars 2004-2005

22 October 2004, L401, 2:15pm

Dr Malcolm Farrow, University of Sunderland

Slipper.

Abstract

Mass spectrometry, in particular `MALDI', or matrix-assisted laser desorption/ionisation, is used to identify samples of protein. The observed mass spectrum is compared with theoretical spectra calculated for known proteins in a large database. A number of algorithms have been proposed. Typically these involve comparing the locations of peaks in theoretical spectra with the locations of peaks identified in the observed spectrum. We outline a Bayesian view of the protein identification problem and consider some of the difficulties.  We compare some of the available algorithms with this Bayesian view and comment on how the strength of evidence is weighed and represented. We propose some means of dealing with the complexities of the problem and discuss further possibilities. Finally we consider the question of how to deal with the possibility that the true protein is not in the database. Some of the principles involved are illustrated by analogy with well-known fairy-tales.

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