Article
Chemistry, Analytical
Simon Becher, Huixin Wang, Michael G. Leeming, William A. Donald, Sven Heiles
Summary: UVPD is a powerful method in top-down proteomics, with sequence coverages exceeding those obtained with other fragmentation methods. Factors influencing protein fragmentation and sequence coverage are actively debated. The study on UVPD experiments on model proteins revealed that sequence coverage increases with higher charge states, and the presence of charge remote and charge directed fragmentation types depending on protonation sites and protein charge states.
Article
Chemistry, Analytical
Henry West, Gavin E. Reid
Summary: Sterols, a class of lipid molecules, play critical functional roles in mammalian biology and are commonly analyzed using high performance liquid chromatography coupled with tandem mass spectrometry. This study explores novel approaches, including 213 nm photodissociation MS/MS and hybrid multistage-MS/MS, for improved structural characterization of sterol lipids, showing promising results in isomeric differentiation of oxysterols. The research demonstrates the potential of using UVPD-MS/MS and hybrid collision induced-MS/MS approaches for enhanced analysis of sterol lipids.
ANALYTICA CHIMICA ACTA
(2021)
Article
Biochemical Research Methods
Michael Lanzillotti, Jennifer S. Brodbelt
Summary: This study compared the effects of 193 nm and 213 nm photons in ultraviolet photodissociation (UVPD) on 5 different proteins and evaluated the differences between the two wavelengths. The results showed that 213 nm UVPD more efficiently generated a specific type of fragment ions, possibly due to increased light absorption at the proline amide bond with 213 nm photons.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2023)
Article
Biochemical Research Methods
Jacob W. Silzel, Ryan R. Julian
Summary: This study explores the use of higher-energy collisional dissociation (HCD) in radical-directed dissociation (RDD) experiments. The results show that RDD-HCD spectra vary considerably as a function of activation energy, with lower energies favoring RDD and higher energies favoring cleavage directed by mobile protons. It is confirmed that RDD generally proceeds via lower-energy barriers relative to mobile-proton-driven dissociation, and the difference between HCD and CID spectra is due to multiple dissociation events.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2023)
Article
Chemistry, Analytical
Alina Theisen, Christopher A. Wootton, Anisha Haris, Tomos E. Morgan, Yuko P. Y. Lam, Mark P. Barrow, Peter B. O'Connor
Summary: In this study, 193 nm ultraviolet photodissociation (UVPD) was combined with 10.6 μm infrared multi-photon dissociation (IRMPD) to provide gentle slow-heating of UV-irradiated ions. The results showed that this method yielded high sequence coverage and increased fragmentation yield. Additionally, IR activation post UVPD further boosted the overall fragmentation yield and the intensity of specific fragments. UVPD was also implemented as a fragmentation method for 2DMS, demonstrating its viability.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Physical
Dababrata Paul, Zhenghai Yang, Arthur G. Suits, David H. Parker, Ralf I. Kaiser
Summary: We investigated the photodissociation dynamics of three xylene isomers C6H4(CH3)2 at 157 nm. We found that the center-of-mass translational energy distributions of C7H7 radicals peaked at 26 kJ mol-1. Despite the ionization energy of the C7H7 tolyl fragment being higher than the energy of a 157 nm photon, the formation of C7H7+ was observed due to the photoionization of vibrationally 'hot' tolyl (C7H7) radicals and/or two-photon ionization. Our experiments suggest the presence of tolyl radicals in the interstellar medium as precursors to methylated polycyclic aromatic hydrocarbons.
CHEMICAL PHYSICS LETTERS
(2022)
Article
Optics
Chen-Xi Hu, Feng He
Summary: Numerical simulations of Rabi flopping during the dissociation of hydrogen molecular ions reveal complex nuclear momentum distributions with multiple angular nodes and maxima, influenced by laser chirp and ellipticity. The Rabi flopping also plays a crucial role in determining the population on the 2p sigma(u) state and consequently affects the dissociation probability. Understanding Rabi flopping in molecular dissociation provides insights for controlling ultrafast molecular dynamics.
Article
Chemistry, Physical
Johanna E. E. Rinaman, Craig Murray
Summary: The photolysis of acetylacetone (AcAc) was studied using velocity-map ion imaging with pulsed nanosecond lasers. The results showed that the dissociation of AcAc occurs with lifetimes longer than the laser pulse duration but shorter than the molecular rotation timescale. It was also found that the excitation of AcAc in the strong UV absorption band leads to the formation of neutral product pairs, possibly via a Norrishtype I mechanism.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Biochemical Research Methods
Luis A. Macias, Jennifer S. Brodbelt
Summary: Disulfide bridges are post-translational modifications that impact the structure and function of proteins. Traditional collisional activation methods are not efficient in cleaving disulfide bonds, making it difficult to analyze proteins that incorporate this feature. Researchers have evaluated the fragmentation pathways enabled by 193 nm ultraviolet photodissociation and photodissociation coupled to electron transfer for the characterization of protein structures incorporating disulfide bonds.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2022)
Article
Chemistry, Physical
Dababrata Paul, Zhenghai Yang, Shane J. Goettl, Aaron M. Thomas, Chao He, Arthur G. Suits, David H. Parker, Ralf I. Kaiser
Summary: In this study, the photodissociation dynamics of astrophysically relevant propyl derivatives at 157 nm has been explored using an ultracompact velocity map imaging setup. The results show distinct center-of-mass translational energy distributions, indicating preferential excitation of low frequency C-H bending modes. C3H7+ was observed, suggesting the presence of isopropyl and possibly normal propyl radicals in the interstellar medium.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Analytical
Shipei Xing, Tao Huan
Summary: Collision-induced dissociation (CID) is a common fragmentation strategy in tandem mass spectrometry (MS2) analysis. This study investigates the occurrence of radical fragment ions (RFIs) in CID MS2 experiments using high-resolution MS2 spectra data. The results show that approximately 65-70% of MS2 spectra of even-electron precursors contain at least 10% RFIs. The percentage of RFIs varies among different compound classes and chemical substructures.
ANALYTICA CHIMICA ACTA
(2022)
Article
Chemistry, Physical
Christopher P. Harrilal, Andrew F. DeBlase, Scott A. McLuckey, Timothy S. Zwier
Summary: The 2C-IRMPD technique utilizes two independently tunable IR sources to control the internal energy content and type of spectrum obtained. It can record near-linear action spectra of both cations and anions with temperatures ranging from 10 to 300 K, as well as IR spectra of single conformers in a conformational mixture. Additionally, it can explore conformational unfolding by recording IR spectra with widely varying internal energy in the ion.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Biochemical Research Methods
Daiki Asakawa, Kazumi Saikusa
Summary: We propose using substituted benzyl ammonium species as thermometer ions to characterize the internal energy distribution of ions produced by electrospray ionization. Experimental results show that the activation of benzyl ammonium species preferentially generates benzyl cations. Calculations reveal that the threshold energies of fragmentation for the tested model ions are significantly lower than those of conventional 4-substituted benzylpyridinium thermometer ions. Furthermore, the internal energies of the ions depend on the radiofrequency voltage of the ion funnel.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2022)
Article
Chemistry, Multidisciplinary
Zhou Min, Shi Yingying, Li Shuqi, Zhang Kailin, Cui Yongliang, Zhang Sen, Zhang Xianyi, Kong Xianglei
Summary: The application of ultraviolet photodissociation (UVPD) in protein top-down mass spectrometry has gained increasing attention in recent years. Results showed that introducing an appropriate amount of collision gas during photolysis in UVPD can improve ion fragmentation and trapping efficiency, generating more abundant fragment ions. The protein sequence coverage in UVPD was found to be related to the charge state of the ions, and further research is needed to improve dissociation efficiency and sequence coverage for lower charged protein ions.
CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE
(2021)
Article
Chemistry, Physical
Sebastian Carrasco, Jose Rogan, J. Alejandro Valdivia, Ignacio R. Sola
Summary: Two novel models developed for H-2(+) molecule and its isotopes demonstrate the anti-alignment with the field in the first excited electronic state, even for the HD+ isotope with a permanent dipole moment. The dissociation of the molecule at angles perpendicular to the field polarization occurs in both the excited and the ground electronic state, as a result of population exchange through a conical intersection. The quantum mechanical dispersion of the initial state is sufficient to cause full dissociation, leading to the conclusion that bond-hardening stabilization in the excited state under a strong field is highly unlikely.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)