Chemoenzymatic synthesis of heparan sulfate and heparin oligosaccharides and NMR analysis: paving the way to a diverse library for glycobiologists

Abstract

A library of diverse heparan sulfate (HS) oligosaccharides was chemoenzymatically synthesized and systematically studied using NMR.

Shotgun ion mobility mass spectrometry sequencing of heparan sulfate saccharides

“…A library of standards representing features found in heparin and HS (including NS/NAc, 2O-/6O/3O-sulfation (2S/6S/3S) and IdoA/GlcA) was collected. This library encompasses a set of disaccharides isolated from heparinasedigested HS, complemented by more extended oligosaccharide structures produced by both chemoenzymatic [25][26][27][28] and chemical synthesis [29][30][31] . The final library included nine disaccharides, ten tetrasaccharides, six hexasaccharides, six octasaccharides, two nonasaccharides and two decasaccharides, in total providing 35 standards (#1-35), and a further standard (#36) described later (See Supplementary Table 1).…”

Using automated glycan assembly (AGA) for the practical synthesis of heparan sulfate oligosaccharide precursors

“…Although byproducts such as deletion sequences formed in AGA can be reduced using capping procedures, the requirement for four iterative glycosylations to achieve three glycosidic linkages in this example highlights that further optimisation of glycosylation procedures in automated synthesis is still essential and represents a key area for exploration by synthetic carbohydrate chemists. 19,33…”

“…Thus the synthesis of pure and homogeneous HS oligosaccharides is crucial for facilitating further biological studies. To date, the synthesis of HS oligosaccharides has been executed via chemoenzymatic, [17][18][19][20] solution-phase [21][22][23][24][25] and solid-phase approaches, 26 relying on many manual operations. But recently, automated glycan assembly (AGA) 27,28 has emerged as a powerful tool for the facile synthesis of biologically important carbohydrate libraries; 29 including sulfated oligosaccharides and their protected precursors.…”

Using heparin molecules to manage COVID‐2019

“…By comparison, a similar synthesis using a purely chemical approach requires 50 synthetic steps with an overall yield < 0.1% 26,27 . The chemoenzymatic synthesis method is now able to produce an unprecedented large oligosaccharide library, providing a potentially unique opportunity to investigate the use of HS to treat severe inflammatory disorders including, perhaps, SARS‐CoV‐2 infection 28 …”