Publications by authors named "A Theisen"

Ultraviolet photodissociation (UVPD) has been shown to be a versatile ion activation strategy for the characterization of peptides and intact proteins among other classes of biological molecules. Combining the high-performance mass spectrometry (MS/MS) capabilities of UVPD with the high-resolution separation of trapped ion mobility spectrometry (TIMS) presents an opportunity for enhanced structural elucidation of biological molecules. In the present work, we integrate a 193 nm excimer laser in a TIMS-time-of-flight (TIMS-TOF) mass spectrometer for UVPD in the collision cell and use it for the analysis of several mass-mobility-selected species of ubiquitin and myoglobin.

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Modern research faces increasingly complex materials with a constant need for new analytical strategies that can provide deeper levels of chemical insight. Ultrahigh resolution mass spectrometry (MS), particularly Fourier transform ion cyclotron resonance (FTICR) MS, has provided a robust analytical foundation. However, MS alone offers limited structural information.

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"Top-down" proteomics analyzes intact proteins and identifies proteoforms by their intact mass as well as the observed fragmentation pattern in tandem mass spectrometry (MS/MS) experiments. Recently, hybrid ion mobility spectrometry-mass spectrometry (IM/MS) methods have gained traction for top-down experiments, either by allowing top-down analysis of individual isomers or alternatively by improving signal/noise and dynamic range for fragment ion assignment. We recently described the construction of a tandem-trapped ion mobility spectrometer/mass spectrometer (tandem-TIMS/MS) coupled with an ultraviolet (UV) laser and demonstrated a proof-of-principle for top-down analysis by UV photodissociation (UVPD) at 2-3 mbar.

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Musculoskeletal complaints are common among children in the primary care setting. Joint pain can be categorized as either inflammatory or noninflammatory (also known as mechanical), and differentiating between these 2 categories affects a physician's differential diagnosis and plan for evaluation. Patients with inflammatory arthritis will frequently present to the primary care physician with musculoskeletal complaints.

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Ultraviolet photodissociation is a fast, photon-mediated fragmentation method that yields high sequence coverage and informative cleavages of biomolecules. In this work, 193 nm UVPD was coupled with a 12 Tesla FT-ICR mass spectrometer and 10.6 μm infrared multi-photon dissociation to provide gentle slow-heating of UV-irradiated ions.

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