Identification of protein biomarkers in the pyrolysis electron ionization high-resolution mass spectrum of Brucella neotomae

Pyrolysis electron ionization high resolution mass spectrometry (Py-EI-HR-MS) has been previously used to identify the source of lipid, carbohydrate and nucleic acid peaks from whole bacterial cells and standards. Py-EI-HR-MS has proven to be a powerful technique for examining biomarker ions in a complex mixture, since most nominal pyrolysis mass spectral peaks are composed of several contributing species. Empirical formula from high-resolution MS data generated from Brucella neotomae, amino acids and proteins for a series of Py-low-resolution mass spectral peaks (m/z 67, 76, 79, 89, 93, 95, 103, 105, 115, 117, 129, and 131) have been calculated. These peaks had been previously found to be statistically important in chemically distinguishing various bacteria. Mechanisms for the formation of pyrolysis and/or electron ionization fragments from the bacterial proteins are presented for ions that were common to the amino acids, protein standards and the bacterial data.