An Orbitrap/Time-of-Flight Mass Spectrometer for Photofragment Ion Imaging and High-Resolution Mass Analysis of Native Macromolecular Assemblies

• Published in: Journal of the American Society for Mass Spectrometry 2023-07, Vol.34 (7), p.1359-1371
• Main Authors: Mathew, Anjusha, Giskes, Frans, Lekkas, Alexandros, Greisch, Jean-François, Eijkel, Gert B., Anthony, Ian G. M., Fort, Kyle, Heck, Albert J. R., Papanastasiou, Dimitris, Makarov, Alexander A., Ellis, Shane R., Heeren, Ron M. A.
• Format: Article
• Language: English
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1021/jasms.3c00053

We discuss the design, development, and evaluation of an Orbitrap/time-of-flight (TOF) mass spectrometry (MS)-based instrument with integrated UV photodissociation (UVPD) and time/mass-to-charge ratio (m/z)-resolved imaging for the comprehensive study of the higher-order molecular structure of macromolecular assemblies (MMAs). A bespoke TOF analyzer has been coupled to the higher-energy collisional dissociation cell of an ultrahigh mass range hybrid quadrupole-Orbitrap MS. A 193 nm excimer laser was employed to photofragment MMA ions. A combination of microchannel plates (MCPs)-Timepix (TPX) quad and MCPs-phosphor screen-TPX3CAM assemblies have been used as axial and orthogonal imaging detectors, respectively. The instrument can operate in four different modes, where the UVPD-generated fragment ions from the native MMA ions can be measured with high-mass resolution or imaged in a mass-resolved manner to reveal the relative positions of the UVPD fragments postdissociation. This information is intended to be utilized for retrieving higher-order molecular structural details that include the conformation, subunit stoichiometry, and molecular interactions as well as to understand the dissociation dynamics of the MMAs in the gas phase.