Characterization of the protein subset desorbed by MALDI from whole bacterial cells.

This study characterizes various features of the proteins that are detected in MALDI mass spectra when whole bacteria cells are analyzed, in an effort to understand why some proteins are successfully detected and many others are not. Forty peaks observed in the mass range 4,000-20,000 Da in the spectra of Escherichia coli K-12 and 11775 are tentatively assigned to proteins in a protein database, and these proteins are characterized by cell location, copy number, pI, and hydropathicity. Those detected originate in the cytosol and generally share the traits of high abundance within the cell, strong bacisity, and medium hydrophilicity.