Chemo-enzymatic strategies for the synthesis of oligosaccharides

Abstract

Carbohydrates represent the most abundant biomass on Earth and thanks to their composition and chemical properties they are involved in an extremely wide range of biological functions. In order to better understand all the phenomena involving carbohydrates it is essential to be able to synthesize them. Chemical synthesis routes are constantly evolving, but often they remain quite complex and take long to perform. More recently an enzymatic approach has emerged as a possible complementary tool to enhance the synthesis of these molecules. In this project we investigate a range of new glycoenzymes and further elucidate novel activity of already known enzymes to provide useful tools for the synthesis of glycans. The reverse action of a bacterial Leloir galactosyltransferase was studied and characterized, leading to a direct application for a cheap and environmentally friendly synthesis of a N-acetyllactosamine building block applied in automated glycan assembly (AGA), demonstrating the complementarity of enzymatic and chemical routes towards the synthesis of oligosaccharides. In addition a novel alpha 1-4 galactosyltransferase has been characterized and applied to the synthesis of analogues of biologically important oligosaccharides. Studying a beta 1-4 galactosyltransferase and its homologous enzymes we were able to identify a promiscuous glucose polymerization activity, leading to the formation of beta 1-4 glucans in a reaction catalysed by two enzymes. We also applied enzymatic sialylation on a glycan synthesized using AGA, leading to the synthesis of oligosaccharides resembling bacterial capsules glycans, a possible motif for glycoconjugate vaccines.

Date of Award	31 Dec 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Sabine Flitsch (Supervisor) & Nicholas Turner (Supervisor)