Electron-capture dissociation

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Electron-capture dissociation (ECD) is a method of fragmenting gas-phase ions for tandem mass-spectrometric analysis (structural elucidation). ECD involves the direct introduction of low-energy electrons to trapped gas-phase ions.[1][2] It was developed by Roman Zubarev and Neil Kelleher while in Fred McLafferty's lab at Cornell University.

Principles

Electron-capture dissociation typically involves a multiply protonated molecule M interacting with a free electron to form an odd-electron ion:

[\mathrm{M} + n\mathrm{H}]^{n+} + e^- \to \bigg[ [\mathrm{M} + n\mathrm{H}]^{(n-1)+} \bigg]^* \to \text{fragments}.

Liberation of the electric potential energy results in fragmentation of the product ion.

ECD produces significantly different types of fragment ions (although primarily c- and z-type, b-ions have been identified in ECD[3]) than other MS/MS fragmentation methods such as electron-detachment dissociation (EDD) (primarily a and x types),[4][5][6][7][8] collision-induced dissociation (CID) (primarily b[9] and y type) and infrared multiphoton dissociation. CID and IRMPD introduce internal vibrational energy in some way or another, causing loss of post-translational modifications during fragmentation. In ECD (and in EDD as well), fragments retain post-translational modifications such as phosphorylation[10][11][12] and O-glycosylation.[13][14] In ECD, unique fragments (and complementary to CID) are observed,[15] and the ability to fragment whole macromolecules effectively has been promising. The low fragmentation efficiencies and other experimental difficulties, which are being studied,[16] have prevented widespread use. Although ECD is primarily used in Fourier transform ion cyclotron resonance mass spectrometry,[17] investigators have indicated that it has been successfully used in an ion-trap mass spectrometer.[18][19][20]

ECD is a recently introduced MS/MS fragmentation technique and is still being investigated.[21][22] The mechanism of ECD is still under debate but appears not to necessarily break the weakest bond and is therefore thought to be a fast process (nonergodic) where energy is not free to relax intramolecularly. Suggestions have been made that radical reactions initiated by the electron may be responsible for the action of ECD.[23]

In a similar MS/MS fragmentation technique called electron-transfer dissociation the electrons are transferred by collision between the analyte cations and reagent anions.[24][25][26][27]

See also

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ Liu and Hakansson, JASMS 18:2007-2013, 2007; Haselmann and Schmidt, RCM 21:1003-1008, 2007; Cooper JASMS 16:1932-1940, 2005.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Creese & Cooper, JASMS 19:1263-1274, 2008.
  11. ↑ Shi et al., Anal. Chem., 73:19–22, 2001.
  12. ↑ Woodling et al., JASMS 18:2137–2145, 2007.
  13. ↑ Mirgorodskaya et al., Anal. Chem. 71:4431–4436, 1999.
  14. ↑ Renfrow et al., JBC 280:19136–19145, 2005.
  15. ↑ Creese & Cooper JASMS 18:891–897, 2007.
  16. ↑ Gorshkov et al., IJMS 234:131–136, 2004.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Baba et al., Anal. Chem., 76:4263–4266, 2004.
  19. ↑ Ding & Brancia, Anal. Chem. 78:1995–2000, 2006.
  20. ↑ Deguchi et al., Rapid Communications in Mass Spectrometry 21: 691–698, 2007.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  23. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  24. ↑ Coon et al., JASMS 16:880–882, 2005.
  25. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  26. ↑ Hamidane et al., JASMS 20:567–575, 2009.
  27. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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