Advancing Protein Analysis: A Low-Pressure Drift Tube Orbitrap Mass Spectrometer for Ultraviolet Photodissociation-Based Structural Characterization

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