Electron Capture Dissociation Cell for Cleaner Protein Sequencing
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Solution Overview
Problem
Conventional mass spectrometry methods face challenges in complete protein sequencing due to incomplete fragmentation and loss of post-translational modifications during collision-induced dissociation, and the complexity of electron capture dissociation spectra from multiple dissociation events hinders accurate peptide sequence reconstruction.
Innovation Solution
A method and system for selectively removing product ions from the interaction region during electron capture dissociation using a quadrupole electrode configuration without auxiliary AC fields, followed by a proton transfer reaction to concentrate product ions at a lower charge state, thereby limiting precursor ions to a single dissociation event and generating predominantly c-type and z-type fragments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electron impact dissociation is used to fragment peptides, then peptide sequencing information is obtained, but the technique is limited to small peptides and cannot effectively analyze larger proteins
Solution Approach 1:
The patent changes the energy parameter from electron impact (high energy) to electron capture (low energy, near thermal energies). This parameter change allows the dissociation process to work effectively for larger proteins while maintaining sequencing accuracy, as the gentler energy transfer prevents fragmentation of large molecular structures while still enabling peptide bond cleavage
Solution Approach 2:
The patent replaces the mechanical electron impact dissociation system with an electron capture dissociation system. Instead of using high-energy electron collisions to break bonds, the system uses low-energy electrons that are captured by protonated peptide ions, leading to dissociation through a different mechanism that preserves structural information and works for larger proteins
2Productivity
If high energy electron impact is applied to induce dissociation, then peptide bonds are broken for sequencing, but the technique is restricted to small peptides due to energy-related limitations
Solution Approach 1:
The patent changes the energy parameter from high energy electron impact to low energy electron capture (near thermal energies). This parameter change enables the dissociation process to be applied to proteins of various sizes, from small peptides to large proteins, while maintaining efficient dissociation through the electron capture mechanism
3Loss of information
If conventional electron impact mass spectrometry is used, then peptide fragmentation is achieved, but the method cannot provide comprehensive sequencing information for complex protein mixtures
Solution Approach 1:
The patent replaces conventional electron impact fragmentation with electron capture dissociation, which provides more comprehensive sequencing information. The electron capture mechanism produces characteristic fragment ions that retain more structural information about the original peptide sequence, enabling better analysis of complex protein mixtures without requiring significantly more complex instrumentation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the efficiency of electron capture dissociation by reducing secondary dissociation events, resulting in a less-convoluted mass spectrum that allows for complete peptide sequencing and improved protein identification.
Implementation Method 1
electron capture dissociation (ECD) has been applied to the analysis of proteins and peptides
Implementation Method 2
The mass analyzer may be any device known in the art capable of analyzing ions
Data Source
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AI summary
Methods and systems are provided herein for selectively removing product ions resulting from an ECD dissociation event from the interaction region of an ECD reaction cell, while other precursor peptide ions continue to undergo ECD within the interaction region, thereby reducing or preventing the occurrence of multiple electron capture events by the product ions. In some aspects, the preferential extraction of product ions from the interaction region during the ECD reaction can occur without an auxiliary AC field being generated within the interaction region. Additionally, in some aspects, the methods and systems disclosed herein can subject the various product ions to a non-dissociative charge reduction via exposure to reagent ions of the opposite polarity so as to selectively concentrate product ions to a lower charge state.