Development of ultraviolet photodissociation mass spectrometry strategies for the characterization of biomolecular structure
Ultraviolet photodissociation (UVPD) is an alternative high-energy ion activation technique implemented to produce information rich tandem mass spectra. Dissociation of biomolecules by UVPD results in structure dependent fragmentation to reveal molecular details that are otherwise undiscernible by traditional tandem mass spectrometry techniques, providing an avenue to rapidly interrogate the structure-function relationship of biologically relevant species. Applied to glycerophospholipids, UVPD is capable of resolving locations of unsaturation and stereospecific numbering of acyl chains, subtle structural features that are traditionally challenging to resolve. In the analysis of intact proteins, UVPD produces excellent sequence coverage that can pinpoint sites of post translational modifications, while providing conformation sensitive fragmentation that also informs changes in higher-order structure that occur upon ligand binding or mutations. Studies covered in this work extend the unique capabilities of UVPD to characterize increasingly complex molecules, explore associations between UVPD resolved structure and disease, and develop an understanding of dissociation mechanisms that govern fragmentation induced by 193 nm photons. Here, the high versatility of this technique was applied to the detailed structural characterization of cardiolipins at the double bond and stereochemistry level by utilizing hybrid techniques that combine collisional activation with UVPD; similarly, UVPD was integrated to both imaging and chromatographic workflows to evaluate fatty acid structure and phosphatidylcholine structure, respectively, as a function of disease state; furthermore, fragmentation of intact proteins was evaluated to discern mechanisms that influence photon-induced dissociation and leveraged to assign paratopes and interpret complex top-down spectra of proteins with disulfide bonds.