Advancing Protein\nAnalysis: A Low-Pressure Drift Tube\nOrbitrap Mass Spectrometer for Ultraviolet Photodissociation-Based\nStructural Characterization

Owing to its ability to generate extensive fragmentation\nof proteins,\nultraviolet photodissociation (UVPD) mass spectrometry (MS) has emerged\nas a versatile ion activation technique for the structural characterization\nof native proteins and protein complexes. Interpreting these fragmentation\npatterns provides insight into the secondary and tertiary structures\nof protein ions. However, the inherent complexity and diversity of\nproteins often pose challenges in resolving their numerous conformations.\nTo address this limitation, we combined UVPD-MS with drift tube ion\nmobility, offering potential to acquire conformationally selective\nMS/MS information. A low-pressure drift tube (LPDT) Orbitrap mass\nspectrometer equipped with 193 nm UVPD capabilities enables the analysis\nof protein conformers through the analysis of arrival time distributions\n(ATDs) of individual fragment ions. ATDs of fragment ions are compared\nfor different backbone cleavage sites of the protein or different\nprecursor charge states to give information about regions of potential\nfolding or elongation. This integrated platform offers promise for\nadvancing our understanding of protein structures in the gas phase.