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Chemically Defined Glycan Libraries for Reference Standards and Glycomics Research (Joint NCI-NIGMS Program)


Summary Glycans play important roles in cell recognition, motility, signaling processes, cell differentiation, cell adhesion, microbial pathogenesis, and immune recognition. Carbohydrate-based high throughput assays (e.g. glycan microarrays, nanoparticles) hold great promise for the rapid analysis of carbohydrate binding proteins (CBPs), elucidation of CBP biology, and the development of diagnostics, vaccines, and therapeutics for a number of diseases, including cancer. However, the utility of these high throughput assays is limited by the paucity of robust biologically relevant glycan libraries available for screening. Glycan standards are also needed to perform structural analysis, especially for monitoring changes in glycosylation that can significantly affect protein function and the safety and efficacy of bio-therapeutics. NCI participates in trans-NIH initiatives to further glycomics research as part of the Alliance of Glycobiologists for Detection of Cancer, which partners with NCI’s Early Detection Research Network, as well as the Glycomics and Glycotechnology Biomedical Technology Research Centers and the Consortium for Functional Glycomics which are funded by NIGMS. Small businesses that develop new glycan libraries for defining the specificities of CBPs, probing the immune response, screening for cancer-associated glycan biomarkers, and enabling glycan structural analysis will more rapidly advance the field of glycomics. Contract offerors must be cognizant of the current cost and intellectual property rights challenges that have restricted the use of chemical libraries in basic, preclinical, and translational research, and be willing to abide by NIH policies pertaining to the sharing and dissemination of unique research resources developed with NIH funding. Abiding by the NIH Principles and Guidelines for Recipients of NIH Research Grants and Contracts on Obtaining and Disseminating Biomedical Research Resources will ensure that libraries and data generated from them will be deposited into existing repositories and databases that will serve as resources for the entire glycobiology community for non-commercial research purposes. Project Goals The goals of this program are to support the synthesis and commercial distribution of robust, well-characterized new carbohydrate libraries that are amenable to being functionalized/linkered for use in high throughput assays, are useful as standards in mass spectrometry (MS) and nuclear magnetic resonance (NMR) applications, and can be used to expand existing screening platforms, structural assays, and additional tool development. These libraries would need to be made with appropriate quality control documentation, and at reasonable cost. The Expanding the Chemical Space for Carbohydrates: Roadmap to Automated Synthesis workshop report, presented to the NIGMS National Advisory Council in 2011, highlights the critical need for comprehensive chemically-defined glycan libraries for: development of screening platforms with sufficient numbers of structures and diversity to cover the major sectors of mammalian glycomes, use as analytical standards, use as substrates for enzymology, and use as building blocks to increase the glycan chemical space with newly identified enzymes. For analytical standards, biologically relevant groups of related structures with emphasis on isomers will be most useful. Compound collections that provide a basis for development of MS or NMR-based experimental conditions for differentiation of closely related structures are highly desirable. Based on current literature, a 10k-12k glycan collection is needed to represent the functional human glycome, and populate a comprehensive glycan array in a manner that would significantly move the field of glycomics forward. Presently, estimates suggest that only 1000 or so glycans have been synthesized for research purposes, and of these, only a few hundred are commercially available. A number of NIH institutes (NIGMS, NCI, NIAID, NHLBI) support specific efforts in glycomics and several others (NIDDK, NIDCR, NICHD, NIAMS) also have interests in glycobiology. Discovery labs in The Alliance of Glycobiologists for Detection of Cancer (, supported by NCI have a current need for libraries of glycans to facilitate structural studies and high-throughput analysis of carbohydrates derived from biological sources. SBIR contracts focused on synthesis of chemically defined glycan libraries that represent important subsets of the human glycome including representative N- and O- linked glycan libraries, glycan structures found on glycosphingolipids, and libraries of glycosaminoglycan oligomers, would speed progress towards a comprehensive mammalian glycan library. Ready access to these reagents is expected to speed progress in the emerging field of glycomics. Compounds must be synthesized and purified utilizing best practices to >98% purity as established by NMR. It is recommended that offerors focus their proposals on developing at least one robust glycan library of significant complexity. Libraries of free, reducing-end glycans required include, but are not limited to: Hybrid-type and complex N-glycan core structures with various multiples of antennae • Hybrid-type N-glycans with all combinations of mannose cores • Complex-type N-glycans with basic structures of bi-, tri- tetra-antennary, and bisected versions of those, terminating in either sialic acid, galactose, or N-acetylglucosamine. Further elaboration of antennae might include lactosamine extensions, fucosylation, or sulfation. Variability of these features in the antennae is also required to distinguish topological isomers. • High mannose-type glycans and isomers. O-glycans • O-glycan Cores 1 and 2, as well as O-glycans bearing fucosylated and sialylated lactosamines of various lengths and degrees of internal fucosylation. Human Blood Group Antigens • ABO blood group (N-Acetylgalactosamine, galactose) antigens (ABO(H) and their variations - A1, A2, H-type 1, H-type 2, H-type 3, H-type 4, etc.). • Lewis blood group (human fucose-containing) antigens (sLex, Lex , Lea, sLea, repeating Lex, etc., on glycolipid, N- and O-glycan backbones, etc.). Glycosphingolipid head groups • Ganglioside-, globoside-, lactosamine-, and neo-lactosamine-based core structures Phosphorylated mannose glycans • P-Man-R and GlcNAc-P-Man-R Glycosaminoglycans (GAGs) • Glycosaminoglycan fragments (especially heparan sulfate oligosaccharides) of 4 to 8 saccharides with/without defined sulfation. Glycopeptides • O-linked core structures on building blocks (such as Fmoc, Ser, or Thr) that can be utilized in peptide synthesis. Phase I Activities and Expected Deliverables • Synthesize a defined library of free reducing-end glycans (20-50 compounds) representative of a sector(s) of the mammalian glycome that is not presently commercially available, under GLP conditions on a pilot scale (~ 200 μg/compound) • Purify these compounds using best practices to >98% purity • Verify structures of the synthesized compounds by NMR • Investigate any packaging issues for the compounds • Provide samples (~50 μg) of all synthesized compounds to an NIGMS-designated screening center for printing on glycan arrays, appropriate validation testing, and subsequent use in NIGMS-funded screening assays • Provide the spectra used to confirm each glycan’s structure as part of product information • Expand the reducing glycan libraries representative of a sector(s) of the mammalian glycome and not presently commercially available to at least 100 compounds • Verify structures of the synthesized compounds by NMR • Scale up the synthesis, purification, structural verification, and packaging of all compounds in the libraries • Provide the spectra used to confirm each glycan’s structure as part of product information • In collaboration with an NIGMS-designated screening center: provide ~ 50 μg of each of the newly synthesized compounds made to expand the libraries for printing on glycan arrays, appropriate validation testing, and subsequent use in NIGMS-funded screening assays • Provide letters of interest from potential customers to purchase the product developed under this contract
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