The Skaggs Institute
for Chemical Biology

Scientific Report 2007

Bioorganic and Synthetic Chemistry

C.-H. Wong, C. Bennett, A. Brik, S. Dean, S. Ficht, W. Greenberg, R. Guy, S. Hanson, Z. Hong, T.-L. Hsu, D.-R. Hwang, M. Imamura, K. Kishikawa, J.-C. Lee, P.-H. Liang, L. Liu, R. Payne, T. Polat, S.-K. Wang, Y.-Y. Yang

We develop new chemical and enzymatic strategies for synthesis of bioactive small molecules and biomolecules. We use the methods to probe carbohydrate-mediated recognition events important in cancer, bacterial infections, inflammation, and viral infections such as influenza and HIV infection.

Synthetic Methods

We have developed a new method, sugar-assisted ligation, for synthesis of homogenous glycoproteins (Fig. 1). The method makes possible the assembly of complex glycoproteins via chemical synthesis, and we are optimizing the techniques to achieve the total synthesis of therapeutic glycoproteins. Using programmable 1-pot oligosaccharide synthesis methods developed in our laboratory, we create glycoarrays on glass slides for high-throughput quantitative analysis of protein-carbohydrate interactions. Using enzymes as synthetic catalysts, we have developed practical new methods of synthesizing molecules such as iminocyclitols, which are inhibitors of glycosidases and other enzymes. Using directed evolution, we are evolving these enzymes to catalyze new reactions and synthesize new molecules, such as the enantiomeric form of naturally occurring sugars.

Fig. 1. Sugar-assisted ligation for synthesis of glycoproteins.

Carbohydrate-Mediated Recognition in Disease

We are using our synthetic methods to discover inhibitors and therapeutic agents in several areas. Current targets include bacterial transglycosidase, sulfotransferases, and glycoprocessing enzymes involved in the biosynthesis of carbohydrates that mediate cancer metastasis, inflammation, and viral infections. Enzymatically synthesized iminocyclitols are being investigated as treatments for osteoarthritis and Gaucher disease. In collaboration with I.A. Wilson, Skaggs Institute, we are developing ligands for CD1 for activation of natural killer T cells. These compounds represent a promising new immunotherapeutic approach to treatment of bacterial and viral infections and of cancer. In collaboration with D.R. Burton, Scripps Research, we are synthesizing multivalent oligomannose antigens for use in development of an HIV vaccine.

Glycoproteomics and Molecular Glycobiology

Using metabolic oligosaccharide engineering, we have developed methods for incorporating tagged sugars into glycans expressed on mammalian cells (Fig. 2). Using click chemistry, we can label the engineered glycans and use fluorescent imaging to compare glycosylation patterns of different cells, such as normal vs cancerous cells or cancer cells vs cancer stem cells. Using tandem mass spectrometry, we are extending this technology to proteome-wide glycoproteomic analysis, to catalog new glycoproteins and identify the effect of different glycans on cellular function.

Fig. 2. Metabolic oligosaccharide engineering and click-activated fluorescent imaging.

Publications

Bennett, C.S., Wong, C.-H. Chemoenzymatic approaches to glycoprotein synthesis. Chem. Soc. Rev. 36:1227, 2007.

Brik, A., Ficht, S., Yang, Y.-Y., Bennett, C., Wong, C.-H. Sugar-assisted ligation of N-linked glycopeptides with broad sequence tolerance at the ligation junction. J. Am. Chem. Soc. 128:15026, 2006.

Brik, A., Wong, C.-H. Sugar-assisted ligation for the synthesis of glycopeptides. Chem. Eur. J. 13:5670, 2007.

Chang, Y.-J., Huang, J.-R., Tsai, Y.-C., Wu, D., Fujio, M., Wong, C.-H., Yu, A.L. Potent immune-modulating and anticancer effects of novel NKT stimulatory glycolipids. Proc. Natl. Acad. Sci. U. S. A. 104:10299, 2007.

Dean, S.M., Greenberg, W.A., Wong, C.-H. Recent advances in aldolase-catalyzed asymmetric synthesis. Adv. Synth. Catal. 349:1308, 2007.

Ficht, S., Payne, R.J., Brik, A., Wong, C.-H. Second-generation sugar-assisted ligation: a method for the synthesis of cysteine-containing glycopeptides. Angew. Chem. Int. Ed. 46:5975, 2007.

Hanson, S., Whalen, L., Wong, C.-H. Synthesis and evaluation of general mechanism-based inhibitors of sulfatases based on (difluoro)methyl phenol sulfate and phenol cyclic sulfamate motifs. Bioorg. Med. Chem. 14:8386, 2006.

Hanson, S.R., Hsu, T.L, Weerapana, E., Kishikawa, K., Simon, G.M., Cravatt, B.F., Wong, C.-H. Tailored glycoproteomics and glycan site mapping using saccharide-selective bioorthogonal probes. J. Am. Chem. Soc. 129:7266, 2007.

Hsu, T.-L., Hanson, S.R., Kishikawa, K., Wang, S.-K., Sawa, M., Wong, C.-H. Alkynyl sugar analogs for the labeling and visualization of glycoconjugates in cells. Proc. Natl. Acad. Sci. U. S. A. 104:2614, 2007.

Kaltgrad, E., Sen Gupta, S., Punna, S., Huang, C.-Y., Chang, A., Wong, C.-H., Finn, M.G., Blixt, O. Anti-carbohydrate antibodies elicited by polyvalent display on a viral scaffold. Chembiochem 8:1455, 2007.

Lee, J.-C., Greenberg, W.A., Wong, C.-H. Programmable reactivity-based one-pot oligosaccharide synthesis. Nat. Protoc. 1:3143, 2006.

Liang, P.-H., Wang, S.-K., Wong, C.-H. Quantification of carbohydrate-protein interactions using glycan microarrays: determination of surface and solution dissociation constants. J. Am. Chem. Soc. 129:11177, 2007.

Michel, M.-L., Keller, A.C., Paget, C., Fujio, M., Trottein, F., Savage, P.B., Wong, C.-H., Schneider, E., Dy, M., Leite-de-Moraes, M.C. Identification of an IL-17-producing NK1.1^NEG cell population involved in airway neutrophilia. J. Exp. Med. 204:995, 2007.

Payne, R.J., Ficht, S., Tang, S., Brik, A., Yang, Y.-Y., Case, D.A., Wong, C.-H. Extended sugar-assisted ligations: development, scope, and applications. J. Am. Chem. Soc. 129:13527, 2007.

Polat, T., Wong, C.-H. Anomeric reactivity-based one-pot synthesis of heparin-like oligosaccharides. J. Am. Chem. Soc. 129:12795, 2007.

Shao, Y.-M., Yang, W.-B., Peng, H.-P., Hsu, M.-F., Tsai, K.-C., Kuo, T.-H., Wang, A.H.-J., Liang, P.-H., Lin, C.-H., Yang, A.-S., Wong, C.-H. Structure-based design and synthesis of highly potent SARS-CoV 3CL protease inhibitors. Chembiochem 8:1654, 2007.

Sugiyama, M., Hong, Z., Liang, P.-H., Dean, S.M., Whalen, L.J., Greenberg, W.A., Wong, C.-H. D-Fructose-6-phosphate aldolase catalyzed one-pot synthesis of iminocyclitols. J. Am. Chem. Soc. 129:14811, 2007.

Sugiyama, M., Hong, Z.-Y., Greenberg, W.A., Wong, C.-H. In vivo selection for the directed evolution of L-rhamnulose aldolase from L-rhamnulose-1-phosphate aldolase (RhaD). Bioorg. Med. Chem. 15:5905, 2007.

Sugiyama, M., Hong, Z.-Y., Whalen, L.J., Greenberg, W.A., Wong, C.-H. Borate as a phosphate ester mimic in aldolase-catalyzed reactions: practical syntheses of L-fructose and L-iminocyclitols. Adv. Synth. Catal. 348:2555, 2006.

Wong, C.-H., Greenberg, W.A. Asymmetric synthesis using deoxyribose-5-phosphate aldolase. In: Asymmetric Synthesis: The Essentials. Christmann, M., Bräse, S. (Eds.). Wiley-VCH, New York, 2007, p. 217.

Yang, Y.-Y., Ficht, S., Brik, A., Wong, C.-H. Sugar-assisted ligation in glycoprotein synthesis. J. Am. Chem. Soc. 129:7690, 2007.

Yu, Z., Sawkar, A.R., Whalen, L.J., Wong, C.-H., Kelly, J.W. Isofagomine- and 2,5-anhydro-2,5-imino-d-glucitol-based glucocerebrosidase pharmacological chaperones for Gaucher disease intervention. J. Med. Chem. 50:94, 2007.