Heparan sulfate synthesis

Abstract

The invention provides an efficient modular chemical synthesis for heparan sulfate oligosaccharides based on orthogonal protection strategies. Modular disaccharide building blocks, themselves the product of a novel combinatorial synthesis, are combined in numerous ways to produce a range of oligosaccharides.

Description

[0001]This application is a continuation-in-part application of international application PCT / US2010 / 029235, filed Mar. 30, 2010, which claims the benefit of U.S. Provisional Application Ser. Nos. 61 / 211,479, filed Mar. 30, 2009, and 61 / 276,627, filed Sep. 14, 2009, each of which is incorporated herein by reference in its entirety.STATEMENT OF GOVERNMENT RIGHTS[0002]This invention was made with Government support under Grant Nos. R01CA088986, P41RR005351-20, and R01DK075069 awarded by the National Institutes of Health. The Government has certain rights in this invention.BACKGROUND OF THE INVENTION[0003]Glycoaminoglycans (GAGs) such as heparin and heparan sulfate (HS) are naturally occurring polydisperse linear polysaccharides that are heavily O- and N-sulfated (Esko et al., Annu. Rev. Biochem. 2002, 71, 435-471; Gandhi et al., Chem. Biol. Drug Des. 2008, 72, 455-482). The interaction between GAGs and proteins can have profound physiological effects on hemostasis, lipid transport and...

AI Technical Summary

Benefits of technology

"The invention provides an efficient and reliable method for producing a wide range of oligosaccharides, particularly sulfated oligosaccharides. This method allows for the synthesis of oligosaccharides that were previously difficult to produce. The invention uses a combination of protecting groups and linkages to create building blocks that can be joined in different ways to create oligosaccharides of various lengths and structures. This method can produce large quantities of oligosaccharides for evaluation and potential use as drugs."

Problems solved by technology

Progress has been hampered by the difficulties of identifying HS-binding motifs for specific proteins.

This difficulty is due to a lack of technology for establishing structure-activity-relations (SAR), which in turn is due to the structural complexity of natural HS and difficulties of preparing well-defined compounds (Karst and Linhardt, Curr. Med. Chem. 2003, 10, 1993-2031; Poletti and Lay, Eur. J. Org. Chem.

Although these approaches make it possible to draw some conclusions about the requirement of particular functionalities for binding or biological activity, they do not allow determination of the structure of binding epitopes.

Natural libraries of HS oligosaccharides have been generated and screened (Guimond and Turnbull, Curr. Biol. 1999, 9, 1343-1346) but sequencing of identified hits is still a technical challenge.

Combining these different disaccharides into larger structures results potentially in enormous structural diversity (Esko et al., Annu. Rev. Biochem. 2002, 71, 435-471).

While it would be useful to screen a relatively large panel of well-defined HS fragments for binding to a target protein, chemical synthesis of the HS fragments has proven difficult and pain-staking.

Only about 100 heparan sulfate oligosaccharides had been reported in the literature as of October, 2009, and synthesizing even a single one can take several months.

2009, 19, 3875-3879; Lee et al., J. Am. Chem. Soc. 2004, 126, 476-477; Noti et al., Chem. Eur. J. 2006, 12, 8664-8686); however, no efficient strategy for the synthesis of a wide range of HS structures has been reported.

These efforts suffered, however, from difficulties in preparing key mono- and disaccharide intermediates, difficulties in removing temporary protecting groups, unreliability in glycosylations and difficulties in the final deprotection.

2003, 3603-3620; Orgueira et al., Chem. Eur. J. 2003, 9, 140-169; Lu et al., Org. Lett. 2006, 8, 5995-5998; Polat and Wong, J. Am. Chem. Soc. 2007, 129, 12795-12800); however, these methods provided unnatural sulfation patterns, were unable to make structures larger than disaccharides or did not demonstrate the convenient preparation of a wide range of structural motifs.

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