Microwave-assisted Automated Glycan Assembly

Abstract

Automated synthesis of DNA, RNA, and peptides provides quickly and reliably important tools for biomedical research. Automated glycan assembly (AGA) is significantly more challenging as highly branched carbohydrates require strict regio- and stereocontrol during synthesis. A new AGA synthesizer enables rapid temperature adjustment from -40 °C to +100 °C to control glycosylations at low temperature and accelerates capping, protecting group removal, and glycan modifications by using elevated temperatures. Thereby, the temporary protecting group portfolio is extended from two to four orthogonal groups that give rise to oligosaccharides with up to four branches. In addition, sulfated glycans and unprotected glycans can be prepared. The new design reduces the typical coupling cycles from 100 min to 60 min while expanding the range of accessible glycans. The instrument drastically shorten and generalizes the synthesis of carbohydrates for use in biomedical and material science.<br>

Recent Developments in Solid-Phase Glycan Synthesis

“…Recently, SPGS integrated with a microwave irradiation device (AGA-MW) was developed to accelerate the preparation of complex glycans, enabling rapid temperature adjustment (–40 to +100 °C) thanks to a dual temperature regulation reaction (DTRR) system. 17 The combination of a constant cooling system with the heating power of microwave irradiation resulted in reduced assembly times. With this setup, the removal of tPGs became much faster due to the elevated temperatures, permitting expansion of the portfolio of tPGs compatible with solid-phase synthesis.…”

“…Moreover, the sulfation step could be accelerated using SPGS integrated with microwave irradiation (AGA-MW), as exemplified for a keratan sulfate tetrasaccharide. 17 Recently, a heparin sulfate (HS) disaccharide library was prepared using an automated machine-aided solid-phase strategy. 29 Pre-synthesized disaccharides were immobilized on lanterns, before being subjected to divergent deprotections and sulfation steps.…”

“…16 Implementation of a microwave (MW) into a home-built AGA machine enabled rapid temperature adjustments, accelerating key steps of the assembly. 17 A flow system established on a pressure-based variable-bed flow reactor (VBFR) permitted the efficient synthesis of oligosaccharides, while providing real-time monitoring of the assembly process. 18 A peptide synthesizer was modified to allow for enzymatic synthesis on solid-phase.…”