Desorption Electrospray Ionisation for Membrane Protein Detection
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Solution Overview
Problem
Current mass spectrometry methods for detecting membrane proteins are limited by the need for membrane proteins to be dissolved in an electrospray solution, restricting flexibility, especially in screening therapeutic agents that bind to membrane proteins.
Innovation Solution
Desorption electrospray ionization source coupled to a mass spectrometer is used to detect membrane proteins by desorbing them from a surface where they are deposited with a solubilizing agent, allowing for ionization and detection without direct introduction into the electrospray solution, enabling the analysis of membrane proteins in an intact, native-like state and their complexes with ligands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If membrane proteins are dissolved in an electrospray solution for mass spectrometry detection, then the proteins can be ionized and detected, but the flexibility of the method is restricted and multiple separate solutions are needed for different complexes
Solution Approach 1:
The invention extracts the membrane protein from the electrospray solution by having the protein adsorb to a solid surface (such as a microtiter plate well). The electrospray solution then only contains the solubilizing agent and ligands, not the protein itself. This allows the same electrospray solution to be used for detecting multiple different membrane protein complexes, greatly improving method flexibility and reducing the number of separate solutions needed.
Solution Approach 2:
Instead of the conventional approach where the protein is in solution and sprayed directly, the invention inverts the process by having the protein adsorbed to a solid surface and then using electrospray to desorb and ionize it. This inversion allows the electrospray solution to contain only small molecules and solubilizing agents that can remain consistent across multiple experiments, while different proteins are introduced by adsorption to the same surface.
2Reliability
If membrane proteins are introduced directly into the electrospray solution, then detection can be performed, but the proteins must be solubilized which may affect their native state
Solution Approach 1:
The invention performs preliminary action by having the membrane protein adsorb to the solid surface before the electrospray detection process. This allows the protein to be in a native-like state during adsorption, and then the electrospray process with appropriate solubilizing agents can gently desorb and ionize the protein while maintaining its structural integrity. The preliminary adsorption step separates the protein from the complex requirements of direct solution preparation.
3Productivity
If traditional mass spectrometry methods are used with detergent micelles, then membrane proteins can be detected, but the process requires buffer exchange and multiple preparation steps
Solution Approach 1:
The invention extracts the membrane protein from the complex buffer exchange process by having it adsorb to a solid surface. This allows the use of a simplified electrospray solution containing only the necessary solubilizing agent and ligands, eliminating the need for buffer exchange steps while maintaining the ability to detect membrane proteins efficiently.
Solution Approach 2:
The solid surface serves multiple functions: it adsorbs the membrane protein, allows for ligand binding, and facilitates electrospray desorption. This multi-functional approach consolidates what would otherwise require multiple separate preparation steps into a single integrated process, improving productivity while reducing procedural complexity.
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 method enhances the flexibility of membrane protein detection and analysis, allowing for the determination of dissociation constants and screening of therapeutic agents, while maintaining the proteins in a native-like state, overcoming the limitations of traditional methods.
Implementation Method 1
desorbing a membrane protein from a surface on which a sample comprising the membrane protein and a solubilising agent has been deposited by applying electrospray to the sample
Implementation Method 2
ionising the membrane protein
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A method for detecting a membrane protein using a desorption electrospray ionisation source coupled to a mass spectrometer comprises: desorbing a membrane protein from a surface on which a sample comprising the membrane protein and a solubilising agent is deposited by applying electrospray to the sample; ionising the membrane protein; and detecting the membrane protein using the mass spectrometer. The method may be used for deriving information about a membrane protein, e.g. its structure or conformation or, where a ligand is present, the stoichiometry and dissociation constant of a complex in which the membrane protein is bound to the ligand.