Biomolecules often contain carbohydrates. Such molecules, namely glycoconjugates, play central roles in cell adhesion, tumor migration, and attachment of pathogens. The conjugation of "natural products" with glycans is not a template-dependent process but is achieved by multiple enzymatic reactions. Because of the nature of the synthetic process, glycans exist as a complex mixture creating a glycoform and thus, the analysis becomes inevitably difficult. Mass spectrometry is one of the most informative, and thus important, tools for the structural analysis of glycans. The obvious advantage of mass spectrometry is the high sensitivity at low femtomole detection levels. A variety of ions can be obtained depending on the adducted cationic species. In order to obtain sequential information, the gas-phase dissociation reaction is used. Among the various techniques, collision-induced dissociation (CID) has been frequently used in the past. Although the technique is proven useful, there are cases that normal CID process is not suitable. This review highlights an emerging technique that focuses on the activation-energy difference between the isomeric glycans, and will complement the current methods. Furthermore, the possible source and the methodology for obtaining useful structural information are discussed.
Keywords: Mass spectrometry, collision-induced dissociation, energy-resolved mass spectrometry, combinatorial library