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

Anjusha Mathew; Frans Giskes; Alexandros Lekkas; Jean-François Greisch; Gert B Eijkel; Ian G M Anthony; Kyle Fort; Albert J R Heck; Dimitris Papanastasiou; Alexander A Makarov; Shane R Ellis; Ron M A Heeren

doi:10.1021/jasms.3c00053

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

J Am Soc Mass Spectrom. 2023 Jul 5;34(7):1359-1371. doi: 10.1021/jasms.3c00053. Epub 2023 Jun 15.

Authors

Anjusha Mathew¹, Frans Giskes¹, Alexandros Lekkas², Jean-François Greisch^{3

4}, Gert B Eijkel¹, Ian G M Anthony¹, Kyle Fort⁵, Albert J R Heck^{3

4}, Dimitris Papanastasiou², Alexander A Makarov^{3

5}, Shane R Ellis^{1

6}, Ron M A Heeren¹

Affiliations

¹ Maastricht MultiModal Molecular Imaging (M4i) Institute, Division of Imaging Mass Spectrometry (IMS), Maastricht University, 6229 ER Maastricht, The Netherlands.
² Fasmatech Science and Technology, Demokritos NCSR, 15310 Agia Paraskevi, Athens, Greece.
³ Biomolecular Mass Spectrometry and Proteomics, Bijvoet Centre for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
⁴ Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands.
⁵ Thermo Fisher Scientific (Bremen) GmbH, 28199 Bremen, Germany.
⁶ Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.

Abstract

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.

Keywords: Orbitrap mass spectrometry; Timepix detector; UV photodissociation; macromolecular assemblies; orthogonal time-of-flight mass spectrometry; photofragment ion imaging.