Unraveling isomeric structures of oligosaccharides by VUVPD and VUVEPD experiments: Towards an unambiguous and complete sequencing of isomers
2014
Ropartz, David | Giuliani, Alexandre | Ralet-Renard, Marie-Christine | Rogniaux-Bonaventure, Hélène
Structural characterization of carbohydrates is of key importance to better understand the structure/property relationships of these molecules, as well as to tailor compounds with enhanced functionalities. Mass spectrometry, with its remarkable sensitivity, rapidity and high information content, is a forefront method for that purpose. However, classical tandem mass spectrometry based on low-energy collision-activated dissociation (LE-CAD) fails in many cases to achieve definitive structural assignments. In this work, we investigated Vacuum Ultra-violet (VUV) synchrotron radiation as activation process for tandem mass spectrometry in positive and negative ion mode. A very interesting setup is implemented on the DISCO beamline which couples the synchrotron radiation with an ion trap mass spectrometer and enables the tuning of the photons energy between 5 and 22 eV. This study is the first one reporting the use of photo-activated dissociation in the VUV for large oligosaccharides. The features of the fragmentation spectra are remarkable and bring straightforward and rich structural information. This led to the comprehensive identification of a large number of structures, including many isomers. This enabled to reach by far the most complete description of the products released from the enzymatic degradation of polysaccharides, bringing insights both on the structure of these polymers as well as on the enzyme specificity. In that context, we believe that the advances brought by VUV activation in tandem MS will meet a widespread interest in the field of structural chemistry of carbohydrates.
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