Electron-capture dissociation

Electron transfer dissociation (ETD) is an ECD-like method with most of the same characteristics [21]. Like ECD, ETD yields abundant peptide backbone c- and z-type ions while often retaining such labile groups as peptide O/TV-glycosylation and phosphorylation [22]. Unlike ECD, ETD can be performed in the presence of an RF field. Here, anions created in a chemical ionization (Cl) source (see Section 2.1.7) are used as electron donors but the fragmentation pathways are essentially the same as for ECD. Commercial linear QIT instruments have recently become available with the ETD option. 

Electron-Transfer Dissociation A new technique, electron-transfer dissociation (ETD), has been introduced for fragmentation of multiply charged peptide ions [29-31], The process is similar to BCD but uses an ion-ion reaction to transfer an electron to the peptide ion. Anthracene anions generated in a Cl source are employed as electron donors. ETD methodology has been adapted in a quadrupole linear ion-trap instrument. Analogous to the ECD process, the transfer of an electron induces fragmentation in the peptide backbone to produce sequence-specific c- and z -type ions. 

For an ion, the cross section for electron capture (EC) roughly increases with the square of the ionic charge [145]. This makes multiply charged ions as produced by electrospray ionization (ESI, Chap. 12) the ideal targets for this process. When a UV laser of 193 nm wavelength (6.4 eV per photon) in the course of ultraviolet photon dissociation (UVPD) experiments erroneously hit a metal surface, elec- 

Irons were deliberated inside the ICR cell. Electron capture by the formed multiply charged protein ions shifted their charge state from 11 to 10 without affecting mass [145]  

The product of EC is a radical ion (Fig. 9.34). The energy from neutralization of one ionic charge (5-7 eV) is transformed into ion internal energy that causes immediate fragmentation, so-called electron capture dissociation (ECD). 

ECD is a technique for trapped ions only. To effectively achieve ECD the electrons must have energies 0.2 eV. Therefore, they are supplied analogously to El from a carefully regulated heated filament [146] externally mounted to the ICR cell. Although a rather recent discovery [145,147], ECD is now widely applied in biomolecule sequencing by means of ESI-FT-ICR-MS [146,148]. The motivation for those numerous ECD applications is due to the fact that ECD yields information complementary to CID [149] and IRMPD [136]. 

Note As one electron charge is neutralized upon EC, the precursor ion for ECD must at least be a doubly charged positive even-electron ion to yield a singly charged radical ion for subsequent dissociation. 

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DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

R. A. Zubarev. Electron-Capture Dissociation Tandem Mass Spectrometry. Curr. Op. Biotechnol, 15(2004) 12-16. 

Source From http //www.matrixscience.com/help/search field help.html, with permission. Abbreviations Q—quadrupole, FT—ion trap, ECD—electron capture dissociation. 

In recent years, a novel approach to protein identification emerged, called top-down sequencing. Here the entire nondigested protein is analyzed. Apart from accurate MW measurement, the protein ion is fragmented by the electron capture dissociation (ECD) method (see Chapter 3). This provides in-depth information on the sequence of protein. Such analysis can be performed only with FTICR instruments (see Section 2.2.6) that ensure high resolution and accuracy but, at the same time, they are exceptionally expensive. However, as very large ions are analyzed, even the high accuracy of FTICR is sometimes not sufficient, and it is recommended that such analyses are accompanied by more traditional bottom-up approaches. 

Cerda, B.A. Horn, D.M. Breuker, K. Carpenter, B.K. McLafferty, F.W. Electron Capture Dissociation of Multiply-Charged Oxygenated Cations. A Nonergodic Process. Eur. Mass Spectrom. 1999, 5,335-338. 

The activation step can alternatively be performed without gas by means of infrared multiphoton dissociation (IRMPD) or electron capture dissociation (BCD) (Chap. 2.12.2). Both IRMPD and BCD, solely require storage of the ions during their excitation by photons or electrons, respectively. It is one of the most charming properties of FT-ICR-MS/MS that even the accurate mass of the fragment ions can be determined. [216,217]... 

McLafferty, E.W., Horn, D.M., Breuker, K, Ge, Y., Lewis, M.A., Cerda, B., Zubarev, R.A. and Carpenter, B.K. (2001) Electron capture dissociation of gaseous multiply charged ions by Eourier-transform ion cyclotron resonance. Journal of the American Society for Mass Spectrometry,... 

Kelleher, N.L., Zubarev, R.A., Bush, K., Eurie, B., Eurie, B.C., McLafferty, E.W. and Walsh, C.T. (1999) Localization of labile posttranslational modifications by electron capture dissociation the case of gamma-carboxyglutamic acid. Analytical Chemistry, 71, 4250-4253. 

Siuti, N., Roth, M.f., Mizzen, C.A., Kelleher, N.L. and Pesavento, J.J. (2006) Gene-specific characterization of human histone H2B by electron capture dissociation. Journal of Proteome Research, 5, 233-239. 

Keywords electron-capture dissociation electron-transfer dissociation electron transfer Rydberg orbital Landau-Zener theory... 

Electron-capture dissociation (ECD) [1] and electron-transfer dissociation (ETD)... 

FT-ICR instruments are also capable of performing MS" experiments. The most popular method of ion activation is sustained off-resonance irradiation (SORI), where ions are excited to a larger cyclotron radius using rf energy, undergo collisions with a neutral gas pulsed into the cell and dissociate. Other methods are available, including infrared multiphoton dissociation (IRMPD)65 and electron capture dissociation (ECD)66 which is of particular value in glyco-peptide analysis (Section VIA). 

K. Hakansson, H. J. Cooper, M. R. Emmett, C. E. Costello, A. G. Marshall, and C. L. Nilsson, Electron capture dissociation and infrared multiphoton dissociation MS/MS of an N-glycosylated tryptic peptide to yield complementary sequence information, Anal. Chem., 73 (2001) 4530-4536. 

F. W. McLafferty, D. M. Horn, K. Breuker, Y. Ge, M. A. Lewis, B. Cerda, R. A. Zubarev, and B. K. Carpenter, Electron capture dissociation of gaseous multiply charged ions by Fourier-transform ion cyclotron resonance, J. Am. Soc. Mass Spectrom., 12 (2001) 245-249. 

N. L. Kelleher, R. A. Zubarev, K. Bush, B. Furie, B. C. Furie, F. W. McLafferty, and C. T. Walsh, Localization of labile posttranslational modifications by electron capture dissociation The case of y-carboxyglutamic acid, Anal. Chem., 71 (1999) 4250 1253. 

A. Stensballe, O. Norregaard-Jensen, J. V. Olsen, K. F. Haselmann, and R. A. Zubarev, Electron capture dissociation of singly and multiply phosphorylated peptides, Rapid Commun. Mass Spectrom., 14 (2000) 1793-1800. 

M. Mormann, B. Macek, A. Gonzalez de Peredo, J. Hofsteenge, and J. Peter-Katalinic, Structural studies on protein O-fucosylation by electron capture dissociation, Int. J. Mass Spectrom., 234 (2004) 11-21. 

Hakansson, K., Emmett, M.R., Hendrickson, C.L. and Marshall, A.G. (2001) High-sensitivity electron capture dissociation tandem FTICR mass spectrometry of microelectrosprayed peptides, Analytical Chemistry 73,... 

Two other ion activation methods were developed to replace the gas molecules as targets by laser beams (photodissociation or infrared multiphoton dissociation IRMPD) or by electron beams (electron capture dissociation ECD). These two methods can be applied to ions that are trapped during their excitations by photons or electrons, respectively. Thus, they are most often used with ion trap or ICR analysers because the residence time and the interaction time are longer. 

Electron capture dissociation (ECD) has recently been developed as an alternative activation method and is now widely used [24,25], The ECD activation method is applied to multiply charged positive ions submitted to a beam of low energy produced by an emitter... 

Zubarev, R.A., Kelleher, N.L. and McLafferty, F.W. (1998) Electron capture dissociation of multiply charged protein cations. A nonergodic process. J. Am. Chem. Soc., 120, 3265-6. 

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