Comparison of collision-induced dissociation and electron-induced dissociation of singly protonated aromatic amino acids, cystine and related simple peptides using a hybrid linear ion trap–FT-ICR mass spectrometer (original) (raw)
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Analytical Chemistry, 1995
A modified ion trap detector has been utilized to obtain high-performance collision-induced dissociation (CID) mass spectra of peptide ions formed by matrix-assisted laser desorption/ionization (MALDI). MALDI ions are trapped while increasing the fundamental radio fiequency field, obviating the need for elevated helium gas pressures, Molecular ion isotopic clusters are then isolated by a reverse-forward-reverse scan sequence. A single species within the isotopic cluster (generally the monoisotopic mass) is then selected for activation. €ha&, modulation of the amplitude of the resonant excitation voltage on the end-cap electrodes, used previously to improve mass calibration in normal mass spectra, is now utilized to provide high mass accuracy for the product ions. The CID mass spectra of several protonated and sodium-cationized peptides are presented and are often characterized by a series of rearrangement ions that can be utilized in the determination of amino acid sequences.
Rapid Communications in Mass Spectrometry, 2003
An electron injection system based on an indirectly heated ring-shaped dispenser cathode has been developed and installed in a 7 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. This new hardware design allows high-rate electron capture dissociation (ECD) to be carried out by a hollow electron beam coaxial with the ion cyclotron resonance (ICR) trap. Infrared multiphoton dissociation (IRMPD) can also be performed with an on-axis IR-laser beam passing through a hole at the centre of the dispenser cathode. Electron and photon irradiation times of the order of 100 ms are required for efficient ECD and IRMPD, respectively. As ECD and IRMPD generate fragments of different types (mostly c, z and b, y, respectively), complementary structural information that improves the characterization of peptides and proteins by FTICR mass spectrometry can be obtained. The developed technique enables the consecutive or simultaneous use of the ECD and IRMPD methods within a single FTICR experimental sequence and on the same ensemble of trapped ions in multistage tandem (MS/MS/MS or MS n ) mass spectrometry. Flexible changing between ECD and IRMPD should present advantages for the analysis of protein digests separated by liquid chromatography prior to FTICRMS. Furthermore, ion activation by either electron or laser irradiation prior to, as well as after, dissociation by IRMPD or ECD increases the efficiency of ion fragmentation, including the w-type fragment ion formation, and improves sequencing of peptides with multiple disulfide bridges. The developed instrumental configuration is essential for combined ECD and IRMPD on FTICR mass spectrometers with limited access into the ICR trap. isolated quadruply charged ions of hecate, and (c) its m/z 710-960 region. The photon irradiation time was 90 ms with a laser power of 80%. A total number of 128 single mass spectra were accumulated.
Journal of the American Society for Mass Spectrometry, 1990
For tandem mass spectrometry, the Fourier transform instrument exhibits advantages for the use of collisionally-activated dissociation (CAD). The CAD energy deposited in larger ions can be greatly increased by extending the collision time to as much as 120 s, and the efficiency of trapping and measuring CAD product ions is many times greater than that found for triple-quadrupole or magnetic sector instruments, although the increased pressure from the collision gas is an offsetting disadvantage. A novel system that uses the same laser for photodesorption of ions and their subsequent photodissociation can produce complete dissociation of larger oligopeptide ions and unusually abundant fragment ions. In comparison to CAD, much more internal energy can be deposited in the primary ions using 193~run photons, sufficient to dissociate peptide ions of m/z > 2000. Mass spectra closely resembling ion photodissociation spectra can also be obtained by.neutral photodissociation (193-nm laser irradiation of the sample) followed by ion photodesorption. (J Am Sot Mass Spectrom 2990, 1, 288-294) M olecular structure elucidation by tandem mass spectrometry (MS/MS) [l-3] is especially promising for the sequencing of oligopeptides [4-61 and phospholipids [7]
Rapid Communications in Mass Spectrometry, 2004
Although electron capture dissociation (ECD) offers many advantages for structural elucidation, a fundamental understanding of all possible processes following electron capture is necessary if ECD is to succeed in the characterization of unknowns. Many biologically active compounds have non-standard structures, e.g, N-alkylation, branching, cyclization, and ester linkages. Here we report ECD of cyclodepsipeptides (valinomycin and beauvericin), including N-methylated structures (beauvericin), branched peptides (AcA 3 K(G 3 )A 3 -NH 2 and A 3 K(G 3 )A 3 -NH 2 ), and oligomers of ε-amino acids (ε-peptides) (Ac(Ahx) 6 K and (Ahx) 6 K) to establish the behavior of such non-standard structures. ECD of cyclodepsipeptides yielded numerous backbone fragments but no charge-reduced species, consistent with a radical cascade mechanism. ECD of ε-peptides resulted in a • and y fragments only, suggesting that the N-C␣ c/z • fragmentation channel is impeded in those structures. ECD of branched peptides resulted in complex fragmentation patterns, characterized by the presence of the immonium related m ion from the modified residue.
Journal of Mass …, 1995
Quasimolecular peptide [ M + H] + ions are generated by matrix-assisted (2,5-dihydroxybeozoic acid/D-fructose) laser desorption/ionization (frequency-tripled Nd: YAG at 355 nm) from leucine enkephalin, bradykinin, the 1101)apeptide Arg-Leu-Cys-Ile-Phe-Ser-Cys-Phe-Arg, angiotensin I, bovine insulin chain B and some of their deuterated derivatives. The ions are cooled and axialized by azimuthal quadrupolar irradiation in the presence of argon collision gas in the 'source' compartment of a dual cubic Penning trap. Following ion transfer to the low-pressure 'analyzer' trap, ultrahigh FT-ICR mass resolving power is obtained for protonated oligopeptide quasimolecular [M + HI + ions: eg. m/Am,,% k: 1 5OOOOO for bradykinin (m/z x 1060) after frequency drift correction and 1OOOOO for insulin B-chain, in which Am,,% is the magnitude-mode peak full width at half-maximum jwak height. These results constitute the highest mass resolving power yet demonstrated for internally-generated MALDI ions at 3 T, and compare favorably with results obtained at much higher-magnetic field with externally-generated ions. High mass resolution is important for resolving adducts and chemical modifications of a peptide or protein and (as demonstrated here) for facile determination of the degree of deuteration from an H/D exchange experiment. Limitations to FT-ICR mass resolving power by Coulombic ion-ion interactions at high ion density in the trap are demonstrated experimentally and discussed.
Journal of the American Society for Mass Spectrometry, 2009
Collision induced dissociation (CID) combined with matrix assisted laser desorption ionizationion mobility-mass spectrometry (MALDI-IM-MS) is described. In this approach, peptide ions are separated on the basis of mobility in a 15 cm drift cell. Following mobility separation, the ions exit the drift cell and enter a 5 cm vacuum interface with a high field region (up to 1000 V/cm) to undergo collisional activation. Ion transmission and ion kinetic energies in the interface are theoretically evaluated accounting for the pressure gradient, interface dimensions, and electric fields. Using this CID technique, we have successfully fragmented and sequenced a number of model peptide ions as well as peptide ions obtained by a tryptic digest. This instrument configuration allows for the simultaneous determination of peptide mass, peptide-ion sequence, and collision-cross section of MALDI-generated ions, providing information critical to the identification of unknown components in complex proteomic samples. (J Am Soc Mass Spectrom 2009, 20, 907-914)
Dynamic Collision-Induced Dissociation of Peptides in a Quadrupole Ion Trap Mass Spectrometer
Analytical Chemistry, 2007
The fragmentation of natural peptides using dynamic collision-induced dissociation (DCID), a novel fragmentation method for quadrupole ion traps, is demonstrated. Using leucine enkephalin as a diagnostic molecule, the fragmentation efficiencies and energetics of DCID are compared with other methods of collisional activation in ion traps such as conventional on-resonance excitation and high-amplitude short-time excitation (HASTE). A typical fragmentation efficiency of ∼20% is achieved for DCID, which is significantly lower than conventional CID (maximum near 80%). Tandem mass spectra of two other peptides, substance P and oxidized insulin r-chain, demonstrate that product ion spectra for DCID are comparable to conventional or HASTE CID. Because DCID achieves fragmentation during the standard mass acquisition scan, no extra time is necessary for onresonance excitation or product ion collection, so analysis times are reduced by a minimum of 10-15% depending on the scanning conditions. DCID therefore offers more tandem mass spectra per second than conventional methods of collisional activation, which could be highly advantageous for bottom-up proteomics separations.
Journal of the American Society for Mass Spectrometry, 2009
We decoupled electron-transfer dissociation (ETD) and collision-induced dissociation of charge-reduced species (CRCID) events to probe the lifetimes of intermediate radical species in ETD-based ion trap tandem mass spectrometry of peptides. Short-lived intermediates formed upon electron transfer require less energy for product ion formation and appear in regular ETD mass spectra, whereas long-lived intermediates require additional vibrational energy and yield product ions as a function of CRCID amplitude. The observed dependencies complement the results obtained by double-resonance electron-capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and ECD in a cryogenic ICR trap. Compared with ECD FT-ICR MS, ion trap MS offers lower precursor ion internal energy conditions, leading to more abundant charge-reduced radical intermediates and larger variation of product ion abundance as a function of vibrational post-activation amplitude. In many cases decoupled CRCID after ETD exhibits abundant radical c-type and even-electron z-type ions, in striking contrast to predominantly even-electron c-type and radical z-type ions in ECD FT-ICR MS and especially activated ion-ECD, thus providing a new insight into the fundamentals of ECD/ETD. (J Am Soc Mass Spectrom 2009, 20, 567-575)