Patent ID: 8153961
Filing Date: 2012-04-10
Classification: G01N,G16B,H01J

Abstract:
1. A method for acquiring and analyzing one or more mass spectra of a sample of a polypeptide or protein, the one or more mass spectra comprising information relating to more than one type of fragment pair, the method comprising: ionizing the sample so as to create ions of the sample; fragmenting selected ions of the sample using a first and a second fragmentation technique so as to create a first set and a second set of fragmented ions, respectively; mass analyzing a mixture of the first and second sets of fragmented ions using a mass analyzer so as to provide the one or more mass spectra; searching a database of polypeptide fragments of a first fragment pair type and a database of polypeptide fragments of a second fragment pair type so as to respectively provide a set of M ranked polypeptide sequences and a set of N ranked polypeptide sequences that best match features of the one or more mass spectra; subtracting synthetic spectra corresponding to each of the M ranked polypeptide sequences and to each of the N ranked polypeptide sequences from the one or more mass spectra so as to provide a first set and a second set of modified mass spectra, respectively; searching the database of polypeptide fragments of the second fragment pair type and the database of polypeptide fragments of the first fragment pair type so as to provide a third set and a fourth set of polypeptide sequences, respectively, wherein the third set and the fourth set of polypeptide sequences respectively provide best matches to features of the first and second sets of modified mass spectra; and creating a cumulative ranking of the polypeptide sequences of the third and fourth sets of polypeptide sequences.