Methods and systems for analyzing proteins by electron capture dissociation

Abstract

Provided herein are methods and systems for selectively removing product ions resulting from ECD dissociation events from an interaction region of an ECD reaction chamber while other precursor peptide ions continue to undergo ECD within said interaction region, The occurrence of multiple electron capture events of the product ions is thereby reduced or prevented. In some aspects, preferential extraction of product ions from the interaction region during the ECD reaction may occur without creating an auxiliary AC field within the interaction region. Furthermore, in some aspects, the methods and systems disclosed herein can subject various product ions to non-dissociated charge reduction by exposure to reagent ions of opposite polarity in order to selectively concentrate the product ions into lower charge states .

Description

[0001] related application [0002] This application claims priority to US Provisional Application No. 62 / 352,836, filed June 21, 2016, which is hereby incorporated by reference in its entirety. technical field [0003] The teachings herein relate to mass spectrometry, and more specifically, to methods and systems for analyzing proteins by electron capture dissociation. Background technique [0004] Mass spectrometry (MS) is an analytical technique used to determine the elemental composition of a test substance, with both quantitative and qualitative applications. For example, MS can be used to identify unknown compounds and / or determine their structure by observing their fragmentation. Recently, MS has played an increasingly important role in proteomics due to the speed, specificity and sensitivity with which MS strategies characterize and identify peptides and proteins. [0005] One strategy for characterizing proteins using MS-based proteomics is the "bottom-up" approa...

AI Technical Summary

Problems solved by technology

[0007] However, one obstacle to the "top-down" ECD approach is the MS resulting from the occurrence of multiple ECD reactions. 2 The complexity of mass spectrometry

Although promoting multiple ECD events reduces the change in the charge state of fragments containing specific sequences, this strategy also presents an obstacle to correctly characterizing the entire peptide sequence due to the increasing presence of internal peptide fragments after multiple dissociation events (i.e., some of the resulting product ions of peptide fragments lack both N- and C-termini)

That is, when the lengths of the c- and z-type fragments become shorter and shorter with each subsequent dissociation of the product ions, the mass spectrometry data cannot effectively reveal the sequence information of the middle part of the peptide, and thus make the Complete reconstruction of peptide sequences becomes difficult

Images