Periodic Reporting for period 2 - SWEETPROMISE (Functional Glycomics Through Chemoenzymatic Synthesis)
Période du rapport: 2023-07-01 au 2024-12-31
Almost all cell surface proteins are modified by covalently-linked carbohydrates and the glycan structures on these glycoproteins are mediators of many physiological and disease processes. Despite their importance, there are no methods available to systematically and efficiently produce libraries of complex glycans to investigate specificities and biology of glycan binding proteins. To address this deficiency, we will develop synthetic methdologies that can provide large collections of glycans having architectures of unprecedented complexity. The methodology will be employed to prepare a series of keratan sulfate oligosaccharides. These glycoconjugates, which are biologically still poorly understood, have been implicated in a multitude of physiological and disease processes. To further broaden the scope of the technology, a chemoenzymatic methodology will be developed to prepare sialosides that at C-4, C-7, C-8 and/or C-9 are modified by acetyl esters. The compounds will be used to develop a designer glycan microarray to identify ligands for glycan binding proteins. The focus will be on immuno-regulatory proteins and viruses that exploit cell surface glycans for infectivity. Cellular arrays will be developed to examine biological properties of hits identified in the microarray screening. The results of the studies will provide critical insight about glycan complexity and recognition by self- and viral glycan binding proteins, and will provide leads for the development of immune-modulators and antiviral agents.
Chemoenzymatic methodologies have been developed to prepare exceptional complex glycans that are involved in health and disease. The focus has been on keratan sulfate which is the least understood proteoglycan. Furthermore, attention has been given to O-acetylated sialosides which have been called Cinderella molecules because of limited knowledge of their biosynthesis, their chemical liabilities, and a lack of methods to prepare panels of O-acetylated sialosides. The newly synthesized glycans made it possible to uncover biosynthetic pathways, to unravel viral binding and recognition of proteins involved in immunity, and to develop analytic methods to identify exact structure of glycans in biological samples.
Synthetic methods will become available to prepare glycans of unprecedented complexity, which will make it impossible to unravel how they are involved in health and disease.