hierarchical-and-programmable-one-pot-oligosaccharide-synthesis

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

This article presents a general experimental protocol for programmable one-pot oligosaccharide synthesis and demonstrates how to use Auto-CHO software for ...

Scripps Research Institute

Heparin (H) and heparan sulfate (HS) belong to the glycosaminoglycan (GAG) family of oligosaccharides, and their sequences and sulfation patterns are known to regulate the functions of various proteins in biological processes. Among these, the 6--sulfation of HS/H contributes most significantly to the structural diversity and binding interactions. However, the synthesis of HS with defined sulfation patterns remains a major challenge. Herein, we report a highly efficient and programmable one-pot method for the synthesis of protected heparin pentasaccharides using thioglycoside building blocks with optimized relative reactivities to allow the selective deprotection and preparation of regiodefined sulfate derivatives.

Programmable one-pot synthesis of heparin pentasaccharides enabling access to regiodefined sulfate derivatives.

The programmable one-pot oligosaccharide synthesis method was designed to enable the rapid synthesis of a large number of oligosaccharides, using the software Optimer to search Building BLocks (BBLs) with defined relative reactivity values (RRVs) to be used sequentially in the one-pot reaction. However, there were only about 50 BBLs with measured RRVs in the original library and the method could only synthesize small oligosaccharides due to the RRV ordering requirement. Here, we increase the library to include 154 validated BBLs and more than 50,000 virtual BBLs with predicted RRVs by machine learning. We also develop the software Auto-CHO to accommodate more data handling and support hierarchical one-pot synthesis using fragments as BBLs generated by the one-pot synthesis. This advanced programmable one-pot method provides potential synthetic solutions for complex glycans with four successful examples demonstrated in this work.

Hierarchical and programmable one-pot synthesis of oligosaccharides.

Fluorinated glycosides are known to resist the glycosidase-catalyzed glycosidic bond cleavage; however, the synthesis of such glycans, especially 3-fluoro-sialic acid (3F-Neu5Ac) containing sialosides, has been a major challenge. Though the enzymatic synthesis of α-2,3-linked 3F-sialosides was reported, until recently there has not been any effective method available for the synthesis of 3F-sialosides in the α-2,6-linkage. In order to understand the biological effect of such modification, we report here a chemical synthesis of 3F-Neu5Ac-α2,6-Gal as a building block for the assembly of 3F-Neu5Ac-containing sialosides and a representative homogeneous antibody glycoform. Our results showed that the sialosides are stable under sialidase catalysis and the rituximab glycoform with a sialylated complex-type biantennary glycan terminated with 3F-Neu5Ac in the α-2,6-linkage (α2,6-F-SCT) has a similar binding avidity as its parent glycoform. These findings open up new opportunities for the development of therapeutic glycoproteins with improved pharmacokinetic parameters.

Synthesis of Sialidase-Resistant Oligosaccharide and Antibody Glycoform Containing α2,6-Linked 3F-Neu5Ac.

Glycosyl phosphates are known as versatile donors for the synthesis of complex oligosaccharides both chemically and enzymatically. Herein, we report the stereoselective construction of modular building blocks for the synthesis of N-glycan using glycosyl phosphates as donors. We have synthesized four trisaccharide building blocks with orthogonal protecting groups, namely, Manβ2GlcNAc(OAc)β6GlcNAc (), Manβ2GlcNAc-β6GlcNAc(OAc) (), Manβ2GlcNAc(OAc)β4GlcNAc () and Manβ2GlcNAcβ4GlcNAc(OAc) () for further selective elongation using glycosyltransferases. The glycosylation reaction using glycosyl phosphate was found to be high yielding with shorter reaction time. Initially, The phthalimide protected glucosamine donor was exploited to ensure the formation of β-glycosidic linkage and later converted to the N-acetyl group before the enzymatic synthesis. The selective deprotection of O-benzyl group was performed prior to enzymatic synthesis to avoid its negative interference.

Article	Year
Programmable one-pot synthesis of heparin pentasaccharides enabling access to regiodefined sulfate derivatives. Chemical science\| PubMed ID: 30310602	2018
Hierarchical and programmable one-pot synthesis of oligosaccharides. Nature communications\| PubMed ID: 30523255	2018
Synthesis of Sialidase-Resistant Oligosaccharide and Antibody Glycoform Containing α2,6-Linked 3F-Neu5Ac. Journal of the American Chemical Society\| PubMed ID: 30969765	2019
Synthesis of Modular Building Blocks using Glycosyl Phosphate Donors for the Construction of Asymmetric N-Glycans. Tetrahedron\| PubMed ID: 30983640	2018

Supriya Dey

Biography

JoVE Journal Publications

Other Publications