The top-down approach to proteomics offers compelling advantages due to the potential to provide complete characterization of protein sequence and post-translational modifications. Here we describe the implementation of 193 nm ultraviolet photodissociation (UVPD) in an Orbitrap mass spectrometer for characterization of intact proteins. Near-complete fragmentation of proteins up to 29 kDa is achieved with UVPD including the unambiguous localization of a single residue mutation and several protein modifications on Pin1 (Q13526), a protein implicated in the development of Alzheimer's disease and in cancer pathogenesis. The 5 ns, high-energy activation afforded by UVPD exhibits far less precursor ion-charge state dependence than conventional collision- and electron-based dissociation methods.
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http://dx.doi.org/10.1021/ja4029654 | DOI Listing |
J Am Soc Mass Spectrom
January 2025
Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, United States.
We report a study of internal covalent cross-linking with photolytically generated diarylnitrile imines of N-terminal arginine, lysine, and histidine residues in peptide conjugates. Conjugates in which a 4-(2-phenyltetrazol-5-yl)benzoyl group was attached to C-terminal lysine, that we call RAAA--K, KAAA--K, and HAAA--K, were ionized by electrospray and subjected to UV photodissociation (UVPD) at 213 nm. UVPD triggered loss of N and proceeded by covalent cross-linking to nitrile imine intermediates that involved the side chains of N-terminal arginine, lysine, and histidine, as well as the peptide amide groups.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
The ultraviolet (UV) photodissociation of pyruvic acid through the absorption of solar actinic flux generates methylhydroxycarbene (MHC) in the atmosphere. It is recognized that isolated MHC can undergo unimolecular isomerization to form acetaldehyde and vinyl alcohol. However, the rates and mechanism for its possible bimolecular reactions with atmospheric constituents, which can occur in parallel with its unimolecular reaction, is not well understood.
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States.
A chlorine-substituted Criegee intermediate, ClCHOO, is photolytically generated using a diiodo precursor, detected by VUV photoionization at 118 nm, and spectroscopically characterized via ultraviolet-visible (UV-vis)-induced depletion of / = 80 under jet cooled conditions. UV-vis excitation resonant with a π* ← π transition yields a significant ground state depletion, indicating a strong electronic transition and rapid photodissociation. The broad absorption spectrum peaks at 350 nm and is attributed to contributions from both (∼70%) and (∼30%) conformers of ClCHOO based on spectral simulations using a nuclear ensemble method.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials (iChEM), Fudan University, Shanghai, 200438, China.
SiO is a widespread molecule found in interstellar space, and its dissociation requires a substantial input of energy due to its high bond energy of 8.34 eV. The present study initially demonstrated across a broad range of ultraviolet (UV) wavelengths (243-288 nm) the one-photon and two-photon dissociation of SiO molecules, which were generated from the laser ablation of a Si rod colliding with an oxygen molecular beam.
View Article and Find Full Text PDFAnal Chim Acta
January 2025
CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address:
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