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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS        
                   School of Computational Sciences	
                           (CSI 898-Sec 001) 
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             Bioinformatics-based Approaches for Microorganism 
                   Identification by Mass Spectrometry

                             Plamen A. Demirev
                      Dept. Chemistry & Biochemistry 
                  University of Maryland, College Park, MD

  A novel approach for rapid microorganism identification, exploiting 
the wealth of information contained in prokaryotic genome and proteome
databases, will be discussed. It is based on determining the masses, Mr, of
a set of proteins detected from intact unknown organisms by matrix-assisted
laser desorption/ ionization time-of-flight mass spectrometry. Matching Mr
against sequence-derived Mr of proteins (found together with their
organismic sources in Internet-accessible proteome databases) and ranking
the organisms, corresponding to matched peaks, results in microorganism
identification. The approach will be illustrated with several
microorganisms whose genomes are completely sequenced. Results from a
statistical analysis of their proteomes will be presented. The multiplicity
(a parameter characterizing the overlap of individual proteins within a
specified Mr window) in pairwise proteome comparisons for the SwissPROT
database will be discussed. Further statistical analysis of proteome
uniqueness as a function of mass accuracy and proteome size suggests a
means to evaluate the rate of false identifications.

                        Monday , October 30, 2000
                                  4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served at 4:15 PM.
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Find the schedule at http://csi.gmu.edu/lcdm/seminar/schedule.html