Thermo Scientific Orbitrap Fusion Lumos Tribrid Mass Spectrometer with UVPD

Importance of the Topic

The detailed characterization of biotherapeutics and lipids is critical for ensuring efficacy, safety and structural understanding. Combining top down and middle down mass spectrometry with ultraviolet photodissociation extends the analytical capabilities to achieve high sequence coverage for intact proteins and precise locating of double bonds in complex lipids.

Objectives and Overview of the Study

This study demonstrates the use of the Orbitrap Fusion Lumos Tribrid mass spectrometer equipped with UVPD for two applications. First, antibody subunits generated by enzymatic digestion and separation are analyzed to achieve comprehensive backbone fragmentation. Second, neutral lipid structures are elucidated by mapping unsaturation sites through diagnostic UVPD fragments not attainable by traditional methods.

Methodology and Instrumentation

Enzymatic digestion followed by chromatographic separation isolates antibody domains including Fd, light chain and Fc2 fragments. UVPD activation in the linear ion trap at high resolution yields rich fragment ion series. Trihybrid activation modes including ETD and EThcD are combined to enhance coverage. For lipid analysis lithiated triacylglycerol precursors undergo UVPD generating diagnostic ions indicative of specific carbon carbon unsaturations. The following instrumentation was employed

• Orbitrap Fusion Lumos Tribrid mass spectrometer with integrated UVPD source
• Dual pressure linear ion trap for MSn experiments
• Class 1 213 nm CryLaS laser system operating at 2.5 kilohertz
• High performance reverse phase chromatography setup

Main Results and Discussion

UVPD delivered 61.2 percent coverage for Fc 2 fragments, 50.9 percent for the light chain and 38.5 percent for Fd subunits. When combined with ETD and EThcD, total coverage increased up to 86.6 percent for Fc 2. Unique cleavage patterns generated by UVPD contributed over 20 percent additional coverage compared to electron based activations. Lipid analyses exhibited clear neutral losses aligned with fatty acid chains and provided unambiguous localization of double bond positions, offering information beyond conventional CID and HCD spectra.

Benefits and Practical Applications

The enhanced fragmentation capabilities enable confident primary sequence verification and post translational modification mapping for monoclonal antibodies. In lipidomics UVPD facilitates precise structural assignment of isomeric species improving biomarker discovery and metabolic research.

Future Trends and Opportunities

Integration of UVPD workflows into routine biopharmaceutical characterization and lipidomics promises streamlined analysis with higher throughput. Advances in data processing algorithms will further exploit the complex fragmentation patterns. Extending UVPD to other classes of biomolecules and coupling with ion mobility represent promising directions for comprehensive structural biology.

Conclusion

UVPD on the Orbitrap Fusion Lumos system significantly advances the structural elucidation of both proteins and lipids by providing complementary fragmentation to established techniques. These developments support deeper molecular insights essential for research and quality control applications.

Reference

• Fornelli et al TP 087 ASMS 2017
• Reid G University of Melbourne 2017