PhD defence: Chemoenzymatic Synthesis and Functional Studies of O-Acetylated Sialoglycans and N-Glycan Derivatives

This thesis develops new chemoenzymatic methods for preparing and studying biologically important carbohydrates.

Well-defined O-acetylated forms of the ganglioside GD3 were synthesized and stably incorporated into cell membranes. Modified red blood cells can therefore be used to study interactions between viral proteins and cell surfaces.

The thesis also reports the first polysialic acid fragments with uniform 7- or 9-O-acetylation. These compounds showed that the human immune protein L-ficolin preferentially recognizes 7-O-acetylated structures. NMR experiments and molecular modelling explained the molecular basis of this selectivity.

Finally, an efficient method was developed to prepare dolichol-linked oligosaccharides. These molecules provide useful tools for studying early steps in N-glycoprotein biosynthesis.