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	{{Mass-spectrometry-stub}}		{{Mass-spectrometry-stub}}
			== Electron-capture dissociation ==
			<gallery>
			File:Schematic_diagram_of_the_combined_ECD_FTICRMS_and_IRMPD_experimental_setup.png\|Schematic diagram of the combined ECD FTICRMS and IRMPD experimental setup
			File:Schematic_of_AP-ECD_source.png\|Schematic of AP-ECD source
			</gallery>

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'''Electron-capture dissociation''' (ECD) is a method of [[fragmentation]] used in [[mass spectrometry]] to analyze highly complex molecules, such as [[proteins]], [[peptides]], and other [[biopolymers]]. Unlike other fragmentation techniques, ECD involves the direct capture of low-energy electrons by multiply-charged molecular ions. This process results in cleavage of the N-Cα bond of the peptide backbone while largely preserving the more labile post-translational modifications, making ECD particularly useful in the study of [[protein structure]] and [[post-translational modifications]].

==Overview==
Electron-capture dissociation was first introduced in 1998 by Roman Zubarev and Neil Kelleher. The technique is especially advantageous for the structural elucidation of [[biomolecules]], as it allows for the differentiation of [[isomeric]] compounds and the detailed mapping of [[protein folding]] and [[protein-protein interactions]]. ECD is performed in [[Fourier transform ion cyclotron resonance]] (FT-ICR) mass spectrometers, although it has also been adapted to other types of mass spectrometers, such as [[Orbitrap]] and [[quadrupole time-of-flight]] (Q-TOF) instruments.

==Mechanism==
In electron-capture dissociation, multiply-charged positive ions (typically generated by [[electrospray ionization]] (ESI) or [[matrix-assisted laser desorption/ionization]] (MALDI)) are reacted with low-energy electrons. The capture of an electron by a positively charged ion leads to the formation of a radical ion, which subsequently undergoes fragmentation. The primary fragmentation pathway in ECD involves the cleavage of the N-Cα bond of the peptide backbone, resulting in c and z• ion series, according to the nomenclature introduced by Roepstorff and Fohlman in 1984.

==Applications==
ECD has found widespread application in the field of [[proteomics]], where it is used to identify proteins and to characterize their post-translational modifications. It is particularly useful for the analysis of [[phosphorylation]], [[glycosylation]], and other modifications that are sensitive to the more energetic fragmentation methods. ECD is also employed in the study of [[protein folding]] and [[conformational changes]], as it allows for the mapping of non-covalent interactions within the protein structure.

==Advantages and Limitations==
The main advantage of ECD is its ability to preserve labile post-translational modifications during fragmentation, providing unique insights into protein structure and function. However, the technique requires the use of specialized equipment, such as FT-ICR mass spectrometers, which can be a limitation for some laboratories. Additionally, ECD is most effective for the analysis of highly charged ions, which may limit its applicability to certain types of samples.

==Comparison with Other Techniques==
ECD is often compared with other fragmentation techniques such as [[collision-induced dissociation]] (CID) and [[electron-transfer dissociation]] (ETD). While CID is more widely available and applicable to a broader range of molecules, it often leads to the loss of labile post-translational modifications. ETD, on the other hand, is similar to ECD in its ability to preserve these modifications but differs in the mechanism of electron transfer.

==Conclusion==
Electron-capture dissociation has significantly advanced the field of mass spectrometry-based proteomics by enabling the detailed analysis of protein structures and post-translational modifications. Despite its limitations, the unique insights provided by ECD into the structure and function of biomolecules make it an invaluable tool in the study of biological systems.

[[Category:Mass spectrometry]]
[[Category:Proteomics]]
[[Category:Biochemistry methods]]

{{Mass-spectrometry-stub}}

Electron-capture dissociation - Revision history

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