Date of Award

Fall 12-17-2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

JUN YIN

Abstract

Oligosaccharides, together with oligonucleotides and oligopeptides, comprise the three major classes of natural biopolymers. Automated systems for oligonucleotide and oligopeptide synthesis have significantly advanced developments in biological science by allowing non-specialists to rapidly and easily access these biopolymers. Researchers have endeavored for decades to develop a comparable general automated system to synthesize oligosaccharides. Such a system would have a revolutionary impact on the understanding of the roles of glycans in biological systems. The main challenge to achieving automated synthesis is the lack of general synthetic methods for routine synthesis of glycans. Currently, the two main methods to access homogeneous glycans and glycoconjugates are chemical synthesis and enzymatic synthesis. Enzymatic glycosylation can proceed stereo- and regiospecifically without protecting group manipulations. Moreover, the reaction conditions of enzyme-catalyzed glycosylations are extremely mild when compared to chemical glycosylations. Over the past few years, methodology towards the automated chemical synthesis of oligosaccharides has been developed. Conversely, while automated enzymatic synthesis is conceptually possible, it is not as well developed.

Inspired by the success of automated oligosaccharide synthesis through chemical glycosylation, a fully machine-driven automated system is built up here for oligosaccharides synthesis through enzymatic glycosylation in aqueous solution. The designed automation system is based on the use of a thermosensitive polymer and a commercially available peptide synthesizer to fully achieve automation process.

An automated platform for chemo-enzymatic glycopeptide synthesis is built up which easily assembles glycopeptides in an organic phase solvent system before extending oligosaccharide residues by enzymatic glycosylation. Our system is based on the use of an amine-functionalized silica resin to facilitate the linkage of the primers needed to begin the chemical or enzymatic synthesis of the target compounds to a solid support. Using our platform, a peptide from mucin 1 with different important glycan epitopes was successfully prepared with a resin transfer step by hand.

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