Ultraviolet Photodissociation: Developments towards Applications for Mass‐Spectrometry‐Based Proteomics

Abstract

Unraveling of all of the information contained in proteomes poses a tremendous chemical challenge, which is balanced by the promise of potentially transformational knowledge. Mass spectrometry offers an unprecedented arsenal of tools for diverse proteomic investigations. Recently, it was demonstrated that ultraviolet light can be utilized to initiate unique and potentially useful fragmentations in peptides and proteins. Either nonspecific dissociation or highly specific dissociation at engineered chromophoric sites is possible following photon absorption. The level of specificity and control over fragmentation in these experiments is greater than with other fragmentation methods. Novel techniques made possible by this technology are poised to make substantial contributions to the field of proteomics.

Photodissociation of TEMPO-modified peptides: new approaches to radical-directed dissociation of biomolecules

“…Photofragmentation is not observed when the wavelength is tuned further to the red (λ > 300 nm), consistent with previous observations of the photolysis of the TEMPO-Bz moiety. 58 Proteins as large as ubiquitin, modified to contain an iodo-tyrosine residue, produce abundant radical ions upon PD 266 (at a similar fluence to that employed herein), through homolysis of the aryl carbon-iodine bond on an excited state surface, 59,60 which is known to occur on the sub-picosecond timescale following excitation. 47 Figure S6), which suggests that both products are formed by similar processes following photo-excitation.…”

Fragmentation ofα-radical cations of arginine-containing peptides

“…For example, radical cations of peptides without additional H atoms are produced by collision-induced dissociation (CID) of ternary metal-ligand-peptide complexes [17][18][19][20][21][22][23][24][25]. In addition, M ϩ· peptide ions have been generated through free radical-initiated reactions [26,27], CID of nitrosopeptides [28], and peptides containing labile serine and homoserine nitrate esters [29], photolysis of peptides containing iodinated tyrosine residues [30,31], and photodissociation of protonated peptides [32,33].Fragmentation of small peptide radical cations has been recently reviewed [7,34]. It is usually initiated by hydrogen abstraction or proton transfer from the initial radical site generated in the ion formation step [35,36].…”

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

“…These methods have shown tremendous success in the structural characterization of numerous classes of molecules, especially for the determination of sequences and modifications of biopolymers like proteins, nucleic acids and carbohydrates [12,13,15,16]. For the determination of peptide sequences, CID generally promotes highly efficient, low-energy fragmentation pathways that yield y and a/b ions through cleavages of amide bonds.…”