Probing High-Order Transient Oligomers using Ion Mobility Mass Spectrometry coupled to Infrared Action Spectroscopy

Understanding and controlling peptide aggregation is critical due to its neurotoxic implications. However, structural information on the key intermediates, the oligomers, is obscured by a cascade of coinciding events occurring at various time and energy scales, which results in complex and heterogeneous mixtures of oligomers. To address this challenge, we have developed the Photo-Synapt, a novel, multidimensional spectrometer that integrates ion mobility mass spec-trometry with infrared (IR) action spectroscopy within a single experiment. By combining three different, orthogonal analytical dimensions, we can select and isolate individual oligomers by mass, charge, size and shape and provide a unique molecular fingerprint for each oligomer. The broad application of this technology is demonstrated by its ap-plication to oligosaccharide analysis from glycoproteins, which are challenging to analyze due to the minute differ-ences between isomers. By integrating infrared action spectroscopy with ion mobility mass spectrometry, this approach adds an analytical dimension that effectively addresses this limitation, offering a unique molecular finger-print for each isomer.