Ultraviolet Photodissociation of tryptic peptide backbones at 213 nm (original) (raw)
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Peptide Photodissociation with 157 nm Light in a Commercial Tandem Time-of-Flight Mass Spectrometer
Analytical Chemistry, 2009
Photodissociation with 157 nm light was implemented in an ABI model 4700 matrix-assisted laser desorption ionization (MALDI) tandem time-of-flight (TOF) mass spectrometer for peptide analysis. With a homemade computer program to control the light timing based on the m/z of each precursor ion, the photodissociation setup was seamlessly automated with the mass spectrometer. Peptide photodissociation in this apparatus yielded fragments similar to those observed in previous experiments with a home-built tandem-TOF mass spectrometer. Peptides having arginine at their C-termini yielded high-energy x-, v-, and w-type fragments, while peptides with Nterminal arginine produced many a-and d-type ions. Abundant immonium ions were also generated. Highquality photodissociation spectra were obtained with as little as 5 fmol of peptides. In the analysis of various tryptic peptides, photodissociation provided much more sequence information than the conventional TOF-TOF collision induced dissociation (CID). Because of the high fragmentation efficiency, sensitivity was not sacrificed to achieve this.
Rapid Communications in Mass Spectrometry, 2006
Protonated precursor ions of phosphorylated peptides containing a tyrosyl residue have been subjected to UV laser-induced dissociation (LID) at a wavelength of 220 nm and to collision-induced dissociation (CID) in an ion trap. As expected, neutral loss of the phosphate group is one of the predominant fragmentation channels during CID together with H 2 O elimination. In contrast, LID leads mainly to the homolytic cleavage of the tyrosyl side chain and a restrained loss of the phosphate group. Interestingly, the intensity of the dephosphorylated fragment ion is greatly minimized when CID is carried out next on the radical precursor ion of the singly and doubly charged species.
Rapid communications in mass spectrometry : RCM, 2014
Mass spectrometry has shown itself as the most efficient tool for the sequencing of peptides. However, de novo sequencing of novel natural peptides is significantly more challenging in comparison with the same procedure applied for the tryptic peptides. To reach the goal in this case it is essential to select the most useful methods of triggering fragmentation and combine complementary techniques. Comparison of low-energy collision-induced dissociation (CID) and higher energy collision-induced dissociation (HCD) modes for sequencing of the natural non-tryptic peptides with disulfide bonds and/or several proline residues in the backbone was achieved using an LTQ FT Ultra Fourier transform ion cyclotron resonance (FTICR) mass spectrometer (Thermo Fisher Scientific, Bremen, Germany) equipped with a 7 T magnet and an LTQ Orbitrap Velos ETD (Thermo Fisher Scientific, Bremen, Germany) instrument. Peptide fractions were obtained by high-performance liquid chromatography (HPLC) separation o...
Photodissociation studies of small peptide ions by Fourier transform mass spectrometry
Organic mass spectrometry, 1993
Fourier transform mass spectrometry was used to study the 193 nm photodissociation of laserdesorbed peptide ions. The output of an excimer laser was split and the two beams were directed sequentially at a sample probe to form ions, and through an aperture in the analyzer cell, to cause photodissociation of trapped ions. A solenoiddriven shutter that is capable of rapid switching (30 ms) between the open and closed states allowed a single laser to be used for both desorption/ionization and photodissociation. Multiple laser pulses were required to fragment a significant fraction of the precursor ions (five pulses yielded 40% dissociation). Collisionally activated dissociation (CAD) mass spectra of the peptides were recorded and compared with the photodissociation mass spectra. Photoactivation of peptide ions produced lower yields of fragment ions formed by loss of small molecules (H,O, NH, , CO, CO,) than did CAD, and produced higher yields of structurally informative sequence ions. For most peptides, the efficiency of ion fragmentaton by photodissociation paralleled the condensed-phase molar absorptivity of the peptide at 193 om. A comparison of these data with those of previous studies suggested that both the ionization method and the observation time (dictated by the type of mass spectrometer) influence the appearance of the photodissociation mass spectrum.
Journal of the American Society for Mass Spectrometry, 2008
y-and b-type fragment ions produced in the collisional dissociation of arginine-terminated peptide ions are photodissociated with 157-nm light in a linear trap. y-type ions are shown to have the same structure as that of intact peptides of the same sequence with the ionizing proton located at the most basic residue(s). For generic b-type ions, the ionizing proton is shown to be sequestered at the N-terminal arginine, which is consistent with the proposed oxazolone structure.
Visible Multiphoton Dissociation of Chromophore-Tagged Peptides
Journal of the American Society for Mass Spectrometry, 2017
The visible photodissociation mechanisms of QSY7-tagged peptides of increasing size have been investigated by coupling a mass spectrometer and an optical parametric oscillator laser beam. The experiments herein consist of energy resolved collision-and laser-induced dissociation measurements on the chromophore-tagged peptides. The results show that fragmentation occurs by similar channels in both activation methods, but that the branching ratios are vastly different. Observation of a size-dependent minimum laser pulse energy required to induce fragmentation, and collisional cooling rates in time resolved experiments show that laser-induced dissociation occurs through the absorption of multiple photons by the chromophore and the subsequent heating through vibrational energy redistribution. The differences in branching ratio between collision-and laser-induced dissociation can then be understood by the highly anisotropic energy distribution following absorption of a photon.
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]
UV Photodissociation of Proline-containing Peptide Ions: Insights from Molecular Dynamics
Journal of the American Society for Mass Spectrometry, 2014
UV photodissociation of proline-containing peptide ions leads to unusual product ions. In this paper, we report laser-induced dissociation of a series of prolinecontaining peptides at 213 nm. We observe specific fragmentation pathways corresponding to the formation of (y-2), (a + 2) and (b + 2) fragment ions. This was not observed at 266 nm or for peptides which do not contain proline residues. In order to obtain insights into the fragmentation dynamics at 213 nm, a small peptide (RPK for arginine-proline-lysine) was studied both theoretically and experimentally. Calculations of absorption spectra and non-adiabatic molecular dynamics (MD) were made. Second and third excited singlet states, S 2 and S 3 , lie close to 213 nm. Non-adiabatic MD simulation starting from S 2 and S 3 shows that these transitions are followed by CC and C-N bond activation close to the proline residue. After this first relaxation step, consecutive rearrangements and proton transfers are required to produce unusual (y-2), (a + 2) and (b + 2) fragment ions. These fragmentation mechanisms were confirmed by H/D exchange experiments.
Journal of the American Society for Mass Spectrometry, 1995
A two-stage linear time-of-flight mass spectrometer is used to investigate the requirements for performance of laser photodissociation of peptide and protein ions. Results are presented that demonstrate that desorption and dissociation laser pulses can be synchronized to irradiate ions that travel at high velocities down the drift tube of a time-of-flight mass spectrometer. For example, 193~run photodissociation of bovine insulin and doubly charged lysozyme is demonstrated, and laser power studies suggest that dissociation is initiated by the absorption of a single 193~run photon. These results are encouraging because they suggest that laser photodissociation of high molecular weight proteins can lead to fragmentation on time scales compatible with time-of-flight mass spectrometry. (1 Am Sot Mass Spectrom 1995, 6, 578-587)
Bifurcating Fragmentation Behavior of Gas-Phase Tryptic Peptide Dications in Collisional Activation
Journal of the American Society for Mass Spectrometry, 2008
Collision-activated dissociation (CAD) of tryptic peptides is a cornerstone of mass spectrometrybased proteomics research. Principal component analysis of a database containing 15,000 high-resolution CAD mass spectra of gas-phase tryptic peptide dications revealed that they fall into two classes with a good separation between the classes. The main factor determining the class identity is the relative abundance of the peptide bond cleavage after the first two N-terminal residues. A possible scenario explaining this bifurcation involves trans-to cis-isomerization of the N-terminal peptide bond, which facilitates solvation of the N-terminal charge on the second backbone amide and formation of stable b 2 ions in the form of protonated diketopiperazines. Evidence supporting this scenario is derived from statistical analysis of the high-resolution CAD MS/MS database. It includes the observation of the strong deficit of a 3 ions and anomalous amino acid preferences for b 2 ion formation