Dissociation electron transfer

Example The direct bond cleavages upon ECD can be used to locate postrans-lational peptide modifications that would be disguised in CID or IRMPD spectra The difference between CID and IRMPD on one side and ECD on the other arises from the loss of most posttranslational modifications prior to backbone cleavage to from b- and y-type ions, while in ECD the chain is immediately cleaved to yield c- and 2-type ions, independent of the peptide sequence [160], Thus, the neutral loss reflects the mass of the modification, e.g., additional 80 u (HPO3) in case of the phosphorylation that can be identified to occur at the tyrosine of the peptide RLpYIFSCFR (Fig. 9.38) [150]. The opportunity to obtain conplementary peptide sequence information is the reason why CID or IRMPD spectra are sometimes combined with ECD spectra for structure elucidation of peptides [136,149,161]. 

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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... 

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. 

J. E. Syka, J. J. Coon, M. J. Schroeder, J. Shabanowitz, and D. F. Hunt. Peptide and Protein Sequence Analysis by Electron Transfer Dissociation Mass Spectrometry. Proc. Natl. Acad. Sci. U.S.A., 101(2004) 9528-9533. 

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

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

McAlister, G. C., Phanstiel, D., Good, D. M., Berggren, W. T., and Coon, J. J. (2007). Implementation of electron-transfer dissociation on a hybrid linear ion trap-orbitrap mass spectrometer. Anal. Chem. 79 3525-3534. 

Syka, J.E.R, Coon, J.J., Schroeder, M.J. et al. (2004) Peptide and protein sequence analysis by electron transfer dissociation mass spectrometry. Proc. Natl. Acad Sci. USA, 101, 9528-33. 

To bring the power of ECD to ion trap analysers, a new ECD-like activation method has been developed [58]. This method, which is called electron transfer dissociation (ETD), uses gas-phase ion/ion chemistry to transfer an electron from singly charged aromatic anions to multiply charged ions. The mechanism of this method and the observed fragmentation pathways are analogous to those observed in ECD. 

S.-I. Wu, A. F. R. Huhmer, Z. Hao, and B. L. Karger, On-line LCMS approach combining collision-induced dissociation (CID), electron transfer dissociation (ETD), and CID of an isolated charge-reduced species for the trace-level characterization of proteins with post-translational modifications, J. Proteome Res., 6 (2007) 4230 -244. 

To address some of the issues associated with CID of phos-phopeptides, new strategies for ion activation/dissociation have been introduced recently in the context of phosphoproteomics. In particular, electron transfer dissociation (ETD) is emerging as a promising new strategy for MS/MS-based phosphopeptide analysis (22, 23). 

Molina H, Horn DM, Tang N, Mathivanan S, Pandey A. Global proteomic profiling of phosphopeptides using electron transfer dissociation tandem mass spectromefry. Proc Natl Acad Sci U. S. A. 2007 104 2199-2204. 

Each electron transfer results in the hydrolysis of two MgATP to two MgADP, and, following electron transfer, dissociation of the two proteins occurs, a step that is rate limiting in substrate reduction. The apparently energetically wasteful evolution of H2 for each N2 reduced is proposed to arise from the requirement for the generation of a reduced site at which N2 binds to displace H2. 

In this model, the FeMoco centers of the MoFe protein are reduced independently by a series of eight one-electron transfers from the Fe protein with concommitant hydrolysis of MgATP. Following each electron transfer, dissociation of the protein-protein complex occurs in a reaction that is rate limiting when dithionite is used as reductant. Following this dissociation, the oxidized Fe protein, with MgADP... 

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