Diverse Heparan Sulfate Oligosaccharide Libraries For Understanding and Therapeutically Manipulating Glycosaminoglycans

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Summary The purpose of this supplementary application is to request funding to purchase a Chemspeed Technologies Flex Liquidose System. This instrument will be utilized to automate the synthesis of heparan sulfate (HS)/heparin oligosaccharides and enable the production of large comprehensive libraries of defined, structurally diverse HS oligosaccharides for biomedical research. The project for the synthesis of HS libraries is currently under the support of the NIGMS SBIR grant (Dr. Vijayakanth Pagadala, 4R44GM134738). The Chemspeed Flex Liquidose workstation will significantly increase our speed and throughput, allowing us to automate the very labor-intensive, late-stage modification and purification steps of HS synthesis. This will drastically reduce the overall time required to synthesize HS oligosaccharides and enable the production of large collections of compounds. Notably, once developed, this system will be the first general, automated platform for glycosaminoglycan (GAG) synthesis. Developing this new capability is essential for completing the proposed oligosaccharide library synthesis and for sustaining the proposed commercialization plan and long-term goals of Glycan Therapeutics. Research Abstract/Summary of Funded Parent Award (Dr. Vijayakanth Pagadala, 4R44GM134738, funding period for phase I: 8/1/2019 to 1/31/2020; funding period for phase II 3/1/2020 to 2/28/2022) The overall goal of this fast-track SBIR program is to synthesize and commercialize the first large, comprehensive libraries of structurally-defined heparan sulfate (HS) oligosaccharides. Glycan Therapeutics is a company that specializes in HS-related research products. In this project, Glycan Therapeutics (Dr. Vijay Pagadala) has teamed up with leading experts in HS synthesis, including Prof. Linda Hsieh-Wilson (California Institute of Technology) and Prof. Xuefei Huang (Michigan State University), to produce large collections of structurally- diverse HS oligosaccharides for biomedical research. HS/heparin glycosaminoglycans (GAGs) are highly sulfated polysaccharides with important roles in many physiological and pathological events. The structural diversity of naturally-occurring HS, which exhibits diverse sulfation patterns, has hindered an understanding of its structure-activity relationships. To date, synthetic methodologies toward HS are mostly target oriented, leading to a small set of oligosaccharides. To enable a deeper understanding of HS biology and investigate its broader therapeutic potential (beyond drugs such as heparin, Lovenox, and Arixtra), the availability of large collections of HS oligosaccharides is critical. In Aim 1, we proposed to expedite the synthesis of key disaccharide building blocks. Rather than starting from monosaccharides, new methods were developed to hydrolyze natural heparin and heparosan polysaccharides to obtain disaccharides.1 These disaccharides were then transformed into suitably-protected building blocks ready for glycosylation and glycan chain extension. Notably, this process reduced the total number of synthetic steps needed to produce the disaccharide building blocks by ~50%. In Aim 2, we proposed to synthesize a comprehensive library of HS tetrasaccharides representing all possible 2-O, 6-O and N-sulfation sequences. A new protecting group strategy was designed to enable access to 256 different HS tetrasaccharides from only four universal building blocks by automated solid-phase synthesis. All tetrasaccharides were designed to be functionalized for bioconjugation and microarray studies. In Aim 3, we proposed to synthesize a library of 13C-labeled oligosaccharide standards carrying a DUA4,5- unsaturated residue at the nonreducing end. A common method for researchers to determine HS composition is to use heparin lyases to degrade HS into disaccharides, followed by disaccharide composition analysis using LC-MS. Currently, there are no commercial sources for stable isotopically-labeled 3-O-sulfated standards. Glycan Therapeutics is synthesizing a series of these standards to enable quantitative analysis of HS composition. In Phase I studies, four key disaccharides (200 mg each), four strategically-protected tetrasaccharide precursors (200 mg each), ten differentially-sulfated HS tetrasaccharides (2 mg each), as well as two 13C-labeled and 3-O- sulfated HS oligosaccharides (1 mg each), were prepared. In the current Phase II studies, the synthesis is being scaled up to produce the universal tetrasaccharide building blocks (10 g each), the 256-member library of HS tetrasaccharides representing all possible 2-O, 6-O and N-sulfation sequences (2 mg each), and a 13C-labeled and 3-O HS oligosaccharide library (28 compounds, 3 mg each). The new HS structures that will become available from this project will cover the entire chemical space of HS tetrasaccharides and represent the largest, most comprehensive HS libraries to date. Successful commercialization of these products will greatly accelerate research on the chemistry and biology of HS and facilitate the development of HS-based therapeutics.