Proposal Defense – Daniel Wu

About the event

Speaker: Daniel Wu

Group: Dr. Brian Clowers

Title: Strategies for Applying Gas-Phase Chemical Labeling in Planar Ion Guides to Mass Spectrometry

Abstract: Mass spectrometry has been the technique of choice for proteomic and lipidomic strategies over the last decade. However, this technique infers composition and lacks any means to directly probe stereochemistry or higher-order structure, which are linked to function in proteins and lipids. This proposal outlines gas-phase chemical labeling strategies to investigate these features on a custom Structures for Lossless Ion Manipulation (SLIM) platform. Hydrogen-Deuterium Exchange (HDX) has been used extensively in solution-phase proteins to probe solvent-accessible regions as a proxy for higher-order structure. Aim 1 will probe these regions in the gas phase and explore any structural changes induced by post-translational modifications of synthetic peptides with known structural motifs. Ozonolysis (OzID) uses reactive ozone to cleave points of saturation in the fatty acid chain of lipids. Aim 2 will use this reaction to differentiate phosphatidylcholine lipid isomers and identify the location of saturations on their fatty acid chains. Fragmentation methods help infer the molecular organization and structure of the analyte from mass spectra. Additionally, specific methods, like UVPD, are amenable to fragmentation of analytes with labile chemical labels without scrambling, enabling tandem chemical labeling and UVPD approaches. Aim 3 will implement an ultraviolet laser for ultraviolet photodissociation (UVPD) fragmentation for the model peptide P1 to confirm usability. Following that, the synthetic peptides with known motifs will be fragmented via UVPD to provide greater granularity in the labeling locations using the resulting fragments. The combination of these techniques on SLIM will offer a novel platform for directly probing gas-phase structural characteristics using mass spectrometry.