Patent ID: 7595485
Filing Date: 2009-09-29
Classification: G16B,H01J,Y10T

Abstract:
1. A method of analyzing product ion data for use in peptide sequence determination by searching a database for matches to mass spectra, the method comprising: (a) subjecting a precursor ion of a sample having a peak abundance to fragmentation by Electron Transfer Dissociation (ETD) to generate ion product data over a spectral range; (b) determining the ion product data quality and utilizing only ion product data of at least a predetermined quality, if any, for further processing in subsequent steps; (c) identifying peaks of the ion product data of the at least predetermined quality that represent first order ion products and higher order ion products, wherein the first order ion products comprise one or more members of the group consisting of charge reduced precursors, electron transfer products anion adducts, side chain losses and hydrogen transfer products and wherein the higher order ion products comprise at least one ion product resulting from a dissociation reaction of a first order ion product; (d) utilizing the ion product data of the at least predetermined quality and the identified peaks of the first and higher order ion product data to determine candidate charge states of the first order ion products; and (e) submitting the identified peaks and the determined candidate charge states to a nucleotide sequence database searching program for performing the peptide sequence determination.