Reactivity-Based One-Pot Synthesis of the Tumor-Associated Antigen N3 Minor Octasaccharide for the Development of a Photocleavable DIOS-MS Sugar Array

Glycan Assembly Strategy: From Concept to Application

Glycans have been hot topics in recent years due to their exhibition of numerous biological activities. However, the heterogeneity of their natural source and the complexity of their chemical synthesis impede the progress in their biological research. Thus, the development of glycan assembly strategies to acquire plenty of structurally well-defined glycans is an important issue in carbohydrate chemistry. In this review, the latest advances in glycan assembly strategies from concepts to their applications in carbohydrate synthesis, including chemical and enzymatic/chemo-enzymatic approaches, as well as solution-phase and solid-phase/tag-assisted synthesis, are summarized. Furthermore, the automated glycan assembly techniques are also outlined.

Toward automated oligosaccharide synthesis

Carbohydrates have been shown to play important roles in biological processes. The pace of development in carbohydrate research is, however, relatively slow due to the problems associated with the complexity of carbohydrate structures and the lack of general synthetic methods and tools available for the study of this class of biomolecules. Recent advances in synthesis have demonstrated that many of these problems can be circumvented. In this Review, we describe the methods developed to tackle the problems of carbohydrate-mediated biological processes, with particular focus on the issue related to the development of the automated synthesis of oligosaccharides. Further applications of carbohydrate microarrays and vaccines to human diseases are also highlighted.

Glycan arrays on aluminum-coated glass slides

We have developed a novel method of immobilizing glycans onto aluminum-coated glass (ACG) slides for potential use in disease diagnosis and drug discovery. The quality of these sugar chips can be assessed by mass spectrometry and fluorescence measurements with high sensitivity. The unique properties of ACG slides include: 1) the metal oxide layer on the surface can be activated for grafting organic compounds such as modified oligosaccharides; 2) the surface remains electrically conductive, and the grafted oligosaccharides can be simultaneously characterized by mass spectrometry and carbohydrate-binding assay; and 3) the slides are more sensitive than transparent glass slides in binding analysis. To demonstrate this, we synthesized a model compound of mannose with a built-in photocleavable linker bound to the ACG slide surface. The molecular weight of the grafted mannose was identified by mass spectrometry, and the slide was subjected to biotinylated ConA binding followed by Cy3-tagged streptavidin detection. This method was further extended to the preparation of glycan arrays containing lactose and the cancer antigen Globo H.