Ion Mobility Cell for HDX Mass Spectrometry Desolvation
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Solution Overview
Problem
Gas-phase hydrogen-deuterium exchange (HDX) in mass spectrometry is hindered by incomplete desolvation and conformational changes in analyte ions due to unevaporated solvent molecules and elevated temperatures, leading to unreliable deuterium incorporation data.
Innovation Solution
An ion mobility cell is used to improve desolvation by introducing a desolvating reagent at the entrance and a HDX reagent at the exit, reducing the impact of solvent interference and maintaining a controlled temperature below 300°C to minimize structural alterations during HDX reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of the ionization chamber or electrospray electrode is increased to promote desolvation, then solvent evaporation is accelerated, but unintended conformational changes in the analyte ions occur
Solution Approach 1:
The ionization chamber is divided into multiple temperature zones: a first region with elevated temperature for desolvation, and a second region with controlled temperature for HDX reactions. This spatial segmentation allows simultaneous optimization of both desolvation efficiency and structural integrity of analyte ions.
Solution Approach 2:
Different regions of the ionization chamber are assigned different thermal conditions tailored to specific functional requirements: high temperature in the desolvation zone to remove solvent, and moderate temperature in the HDX zone to maintain protein conformation. Each region's quality is optimized for its specific purpose.
2Productivity
If gas-phase HDX is performed with analyte ions before complete desolvation, then HDX reactions can occur, but deuterium incorporation is reduced due to solvent barrier
Solution Approach 1:
Desolvation is performed as a preliminary step before HDX reactions in the first region of the ionization chamber. By removing solvent molecules beforehand, the barrier to HDX reagent access is eliminated, ensuring accurate deuterium incorporation measurements in subsequent regions.
Solution Approach 2:
A controlled environment in the first region acts as an intermediary zone that facilitates complete desolvation of analyte ions before they enter the HDX reaction region. This intermediate step ensures that ions are properly prepared for accurate HDX measurements without direct solvent interference.
3Temperature
If higher desolvation temperatures are used, then solvent evaporation is improved, but labile protons normally buried in folded structure are exposed and undesirably exchanged
Solution Approach 1:
The ionization chamber is segmented into distinct functional regions: a high-temperature first region for desolvation and a moderate-temperature second region for HDX reactions. This segmentation prevents conformational changes by isolating the high-temperature exposure to only the desolvation phase, protecting the analyte structure during the HDX measurement phase.
Solution Approach 2:
The process maintains continuous control over temperature and reaction conditions through sequential regions. Analyte ions experience controlled desolvation followed by immediate transfer to a protected environment for HDX reactions, ensuring continuous protection against unwanted conformational changes while maintaining productive HDX measurements.
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 accuracy of HDX data by ensuring complete desolvation and reducing unintended conformational changes, resulting in more reliable deuterium incorporation measurements.
Implementation Method 1
a curtain gas comprising a desolvating reagent is introduced into a first region of the chamber located between the curtain plate and the entrance end such that at least a portion of the curtain gas and the charged micro-droplets are transported between the plurality of electrodes so as to desolvate solvent within the charged micro-droplets
Implementation Method 2
a throttle gas comprising a HDX reagent is introduced into a second region of the chamber located between the exit end and the orifice plate. The analyte ions are transported from the exit end through the second region and into the vacuum chamber via an orifice in the orifice plate. In certain aspects, the analyte ions can interact with the HDX reagent as they pass through the second region. For example, in some aspects, transporting the analyte ions through the second region containing the HDX reagent comprises replacing one or more protons of at least one analyte ion with deuterium
Implementation Method 3
In a typical electrospray ionization (ESI) process, a liquid sample containing an analyte of interest is discharged into an ionization chamber via an electrically conductive needle, electrospray electrode, or nozzle, while an electric potential difference between the electrospray electrode and a counter electrode generates a strong electric field within the ionization chamber that electrically charges the liquid sample
Data Source
AI summary
Systems and methods are disclosed for utilizing an ion mobility cell to improve desolvation prior to interaction with a hydrogen-deuterium exchange reagent, thereby improving the accuracy of the HDX data generated by MS and reducing the effects of conformational changes that can occur with increased temperatures.