Ultraviolet Photodissociation of Carboxylate-Derivatized Peptides in a Quadrupole Ion Trap

Abstract

The fragmentation patterns obtained by ultraviolet photodissociation (UVPD) and collisioninduced dissociation (CID) in a quadrupole ion trap mass spectrometer were compared for peptides modified at their C-termini and at acidic amino acids. Attachment of Alexa Fluor 350 or 7-amino-4-methyl-coumarin chromophores at the C-terminal and acidic residues enhances the UV absorptivity of the peptides and all fragment ions that retain the chromophore, such as the y ions that contain the chromophore-modified C-terminus. Whereas CID results in the formation of the typical array of mainly y-type and a/b-type fragment ions, UVPD produces predominantly a/ b-type ions with greatly reduced abundances of y ions. Immonium ions, mostly ones from aromatic or basic amino acids, are also observed in the low m/z range upon UVPD. UVPD of peptides containing two chromophore moieties (with one at the C-terminus and another at an acidic residue) results in even more efficient photodissociation at the expense of the annihilation of almost all diagnostic b and y ions containing the chromophore.

Photodissociation mass spectrometry: new tools for characterization of biological molecules

“…178–185 In contrast to the bond-specific cleavages promoted by UVPD described above, in this case a chromophore is attached to the molecule of interest via a covalent tagging reaction for a different purpose. The tagging reaction appends a chromophore that endows the molecules with high photoabsorption cross-sections not exhibited by the non-tagged molecules.…”

“…The requirement for a suitable chromophore can be exploited strategically in wavelength-selective, chromophore-specific applications, as reported in several recent applications. [178][179][180][181][182][183][184][185] In contrast to the bond-specific cleavages promoted by UVPD described above, in this case a chromophore is attached to the molecule of interest via a covalent tagging reaction for a different purpose. The tagging reaction appends a chromophore that endows the molecules with high photoabsorption cross-sections not exhibited by the non-tagged molecules.…”

“…However, tagging these molecules with a chromophore at 350 nm converts them into molecules that will absorb photons from the third harmonic of a Nd:YAG laser (355 nm) or an XeF excimer laser (351 nm). 58,[178][179][180][181][182][183] This chromophore tagging concept has also been demonstrated using visible photons, specifically 473 nm or 532 nm. 184,185 One of the first studies illustrating the strategy of attaching chromophores to molecules to give them unique UV photodissociation behavior was reported in 2007.…”

Symmetry of Charge Partitioning in Collisional and UV Photon-Induced Dissociation of Protein Assemblies

“…An interesting alternative fragmentation method explored is surface induced dissociation (SID). Noteworthy, SID was shown to produce preferably symmetric charge partitioning for protein assemblies, which was attributed to its more prompt, high-energy fragmentation mechanism. ,, Another newcomer in the field of protein assembly dissociation techniques is ultraviolet photodissociation (UVPD), which utilizes the natural chromophores present in the backbone of peptides and proteins to absorb highly energetic photons (λ = 193 nm) emitted from a laser. − The technique may provide prompt fragmentation at an activation time scale close to the energy deposition in SID, and could thus potentially prove to be a beneficial method for probing of assembly composition and topology. In this study, we report the modification of an Orbitrap-based mass spectrometer with Extended Mass Range (EMR) capabilities to support UVPD.…”

Increasing specificity of tandem mass spectrometry by laser‐induced dissociation

“…In a pioneering study, N‐terminal attachment of dinitrophenyl on amino acids and small peptides allows fragments to be produced upon photoexcitation by 333–365 nm and 454–514 nm photons . Other studies have been reported that illustrate the strategy of attaching chromophores to molecules at the N‐ or C‐terminus (and acidic residues) in order to increase their light absorption properties at 355 or 351 nm . Fragmentation patterns were also simplified significantly, exhibiting only b ions, thus allowing de novo peptide sequencing to be improved.…”