Over the last 20 years, major advances in genomics and proteomics have been achieved. However, the field of glycomics has lagged significantly. There are many hurdles associated with the study of glycoproteins and their prevalence in biological systems. Unlike nucleic acid and protein sequences, oligosaccharide sequences are not encoded, but are likely dependent on environmental factors. In order to study glycoproteins and their roles in biochemical and immunological systems, it is important to obtain pure, measureable quantities of specific glycans. However, it is almost impossible to isolate glycans from natural sources, since they exist as microquantities of heterogeneous mixtures. O-mannosylated proteins comprise approximately 30% of O-glycoproteins in the brain. They are critical for growth and development and disruption of their biosynthesis results in various forms of congenital muscular dystrophy. Despite their important biological implications, the function and prevalence of O-mannosylated glycoproteins is not well understood. The objective of the proposed research is to chemically synthesize bi-antennary O-mannose oligosaccharides. Standard organic synthesis techniques will be used to prepare monomers, which will then be combined into oligosaccharides using an automated oligosaccharide synthesizer in collaboration with Prof. Nicola Pohl at Indiana University. The long term goal of this project is to study receptors specific to these glycans. In particular, microarrays of the glycans can be used to identify the specific O-mannose epitopes for antibodies which are known to bind generally to O-mannose glycans. Once antibodies have been identified, those antibodies may be used to identify additional glycoproteins containing O-mannose glycans, which will make important contributions to the field of glycomics. In addition, chemical synthesis of O-mannose glycans may also contribute to the understanding of how and why proteins are glycosylated, which will contribute to the larger field of proteomics and epigenetics.
Relevance of Research
All cells are coated with chains of sugars, or oligosaccharides, which serve many important purposes in cell biology and immunology. However, the oligosaccharides are present in very small quantitites which make them difficult to isolate and study. Therefore, in order to better understand the role of oligosaccharides in biological processes, specifc oligosaccharides will be synthesized in the laboratory and evaluated for their biolgical importance.