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Metal ion as structural probe for carbohydrate characterization by ion mobility spectrometry and tandem mass spectrometry
Carbohydrates play central roles in numerous areas of biochemistry. Detailed molecular characterization of carbohydrate structures remains distinctly challenging, partly due to the possibility for numerous isomeric structures. Although the structural differences among carbohydrate isomers can be exceedingly subtle, the corresponding biological consequences are often remarkably pronounced. Thus, methods for ascertaining the fine structures of complex carbohydrates are of tremendous importance for establishing a more thorough understanding of glycobiology. Ion mobility spectrometry (IMS), which allows for millisecond-order gas-phase sorting of ions based on their size-to-charge ratios, has shown significant potential for the rapid differentiation of carbohydrate isomers; nevertheless, much of this potential remains undeveloped. In addition, tandem mass spectrometry (MS/MS) has been of longstanding interest for carbohydrate structural characterization; however, the most common MS/MS methods currently available are often of limited facility for discerning isomeric carbohydrates. This dissertation describes the development of novel approaches for the discrimination of carbohydrate isomers by IMS and MS/MS. Chapter I provides a primer on the structural complexity of carbohydrates, as well as an overview of IMS and MS/MS techniques as applied to carbohydrate analysis. Chapter II describes a study of group I metal cations as structural probes to improve isomer discrimination by IMS. Chapter III demonstrates the exploitation of carbohydrate / group II metal ion interactions in concert with gas phase ion-ion reactions to enhance the capacity of IMS and MS/MS to discriminate isomeric carbohydrates. Chapter IV further elaborates on the potential of divalent metal ion adduction and gas phase ion-ion chemistry to resolve carbohydrate isomers. Chapter V describes the development of an MS/MS approach for discrimination of isomeric carbohydrates using metal ion adduction and gas-phase ion chemistry. The unique fragmentation pathway exhibited by each isomer provided previously unrealized opportunities for isomer discrimination. Chapter VI focuses on combining the dimensions of metal cation probe, ion-ion chemistry, and vibrational activation energy to distinguish increasingly intricate carbohydrate structures. Overall, the combination of metal ions as structural probes and gas-phase ion chemistry to modulate the electronic properties of these probes appears to be a fruitful avenue for further development of IMS and MS/MS based glycoanalytical tools.^
Huang, Yuting, "Metal ion as structural probe for carbohydrate characterization by ion mobility spectrometry and tandem mass spectrometry" (2016). ETD collection for University of Nebraska - Lincoln. AAI10247214.