Fragmentation of oligopeptide ions using ultraviolet laser radiation and Fourier transform mass spectrometry

Bowers, William D.; Delbert, S.; Hunter, Richard; McIver, Robert T.

doi:10.1021/ja00335a094

Cited by 143 publications

(103 citation statements)

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“…Absorption of UV/vis photons by ions occurs by resonant photon absorption from the ground to an excited electronic state and commonly results in photodissociation of the excited ion. Photodissociation of peptides and small proteins has been achieved using 193 nm (6.42 eV) photons (Bowers et al, 1984;Bowers, Delbert, & McIver, 1986;Williams, Furlong, & McLafferty, 1990;Beu et al, 1993). However, photodissociation of larger proteins (ubiquitin ions, 8.6 kDa) resulted in formation of small, uninformative fragment ions (Beu et al, 1993).…”

Section: Multiphoton Dissociationmentioning

confidence: 99%

Activation of large lons in FT‐ICR mass spectrometry

Laskin

Futrell

2004

Mass Spectrometry Reviews

177

146

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The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition-the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single-and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI)-the simplest and most robust means of introducing the multiple collision activation process-is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules can be effected using IR or UV/vis lasers and generally requires tuning lasers to specific wavelengths and/ or utilizing high flux, multiphoton excitation to match energy levels in the ion. Photodissociation of complex ions is much easier to accomplish from the basic physics perspective. The quasi-continuum of vibrational states at room temperature makes it very easy to pump relatively large amounts of energy into complex ions and infrared multiphoton dissociation (IRMPD) is a powerful technique for characterizing large ions, particularly biologically relevant molecules. Since both SORI-CID and IRMPD are slow activation methods they have many common characteristics. They are also distinctly different because SORI-CID is intrinsically selective (only ions that have a cyclotron frequency close to the frequency of the excitation field are excited), whereas IRMPD is not (all ions that reside on the optical path of the laser are excited). There are advantages and disadvantages to each technique and in many applications they complement each other. In contrast wi...

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Section: Multiphoton Dissociationmentioning

confidence: 99%

Activation of large lons in FT‐ICR mass spectrometry

Laskin

Futrell

2004

Mass Spectrometry Reviews

177

146

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“…Photodissociation of di-and tripeptide ions with 193 nm light was first reported by Bowers et al using an FTICR mass analyzer [6]. Larger peptides have also been investigated with this technique [7][8][9].…”

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confidence: 99%

Factors that impact the vacuum ultraviolet photofragmentation of peptide ions

Thompson

Cui

Reilly

2007

J. Am. Soc. Mass Spectrom.

101

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Several groups have investigated the photodissociation of peptide ions with ultraviolet light. Significant differences have been reported with 157 and 193 nm excitation. Recent studies have shown that the mass analyzer can also influence the observed photofragment distribution.Comparison of experiments using different peptides, wavelengths, and mass analyzers is undesirably complicated. In the present work, several peptides are analyzed with both 157 and 193 nm photodissociation in tandem-TOF and linear ion trap mass spectrometers. The results indicate that the fragment ion distribution can be influenced by both the photodissociation wavelength and the mass analyzer. The two wavelengths generate similar spectra in an ion trap but quite different results in a tandem

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“…Although a variety of excitation methods have been applied to generate peptide fragments, including blackbody radiation [3], IR multiphoton excitation [4], UV laser excitation [5][6][7][8][9], and collisions with gas-phase molecules [1] or surfaces [10], low-energy collisional activation is the most commonly employed technique. These methods have been reviewed recently [11].…”

mentioning

confidence: 99%

Pathways of Peptide Ion Fragmentation Induced by Vacuum Ultraviolet Light

Cui

Thompson

Reilly

2005

J. Am. Soc. Mass Spectrom.

119

181

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One Hundred Fifty-Seven nm photodissociation of singly protonated peptides generates unusual distributions of fragment ions. When the charge is localized at the C-terminus of the peptide, spectra are dominated by x-, v-, and w-type fragments. When it is sequestered at the N-terminus, a-and d-type ions are overwhelmingly abundant. Evidence is presented suggesting that the fragmentation occurs via photolytic radical cleavage of the peptide backbone at the bond between the ␣-and carbonyl-carbons followed by radical elimination to form the observed daughter ions. Low-energy fragmentation appears to be well described by the mobile proton model according to which vibrational excitation of the analyte leads to charge mobility [12]. Transfer of the charge proton to either the backbone carbonyl oxygen or amide nitrogen enables charge-induced cleavage of the peptide backbone. This process yields primarily b-and y-type fragment ions according to the standard nomenclature shown below [13,14].Higher energy activation methods involving collisions with gas molecules or surfaces can enable chargeremote fragmentation [15][16][17]. However, even in these cases, apparently, protonated peptides still generate some fragments through charge-directed processes [17]. Immobilization of the charge, either by using metal adducts [18] or charged chemical modifications [19 -22], has been used to inhibit charge-directed fragmentation. In these cases, primarily a-, d-, and w-type fragments are observed. Several mechanisms have been proposed for charge-remote peptide fragmentation, some involving homolytic radical cleavage [14,23].Electron capture dissociation (ECD) [24] and the recently reported electron-transfer dissociation (ETD)[25] appear to be nonthermal processes. These phenomena generate c-and z-type fragment ions upon the addition of an electron to a multiply charged protein or peptide ion. Two mechanisms have been proposed, one involving reactions of a free hydrogen atom generated when an electron is captured by a charged site on the analyte ion [26], and the other involving localization of the ϳ6 eV of energy that is generated upon charge neutralization. This energy then induces fragmentation through an excited electronic state [27]. Implicit in this second mechanism is the suggestion that techniques which excite appropriate electronic states can lead to unique, nonergodic fragmentation even for molecules as large as peptides and proteins [24,27]. This can occur if ions reach a dissociative electronic state and fragment before the energy is redistributed throughout the molecule. Electronic to vibrational relaxation, resulting in nonspecific excitation is an important competing process that often inhibits nonergodic processes, and rates of relaxation are predicted to increase with the size of the molecule [28].Lasers are powerful tools that can also be used to excite molecules to specific energy levels with either multiphoton or single photon processes. Light is not affected by the electric or magnetic fields of mass spectrometers, s...

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Fragmentation of oligopeptide ions using ultraviolet laser radiation and Fourier transform mass spectrometry

Cited by 143 publications

References 0 publications

Activation of large lons in FT‐ICR mass spectrometry

Activation of large lons in FT‐ICR mass spectrometry

Factors that impact the vacuum ultraviolet photofragmentation of peptide ions

Pathways of Peptide Ion Fragmentation Induced by Vacuum Ultraviolet Light

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