Bio-orthogonal Therapeutics

Click chemistry is one of the most significant inventions in the history of science. Nobel Prize of Chemistry in 2022  was awarded to Karl Barry Sharpless, Morten P. Meldal and Carolyn R. Bertozzi for their invention of click chemistry. Click chemistry can happen under physiological conditions without side products. Click chemistry is modular in nature, meaning that you can click almost any molecule, such as a drug or a fluorophore, to a target molecule that contains a clickable moiety. Click chemistry is revolutionary and is comparable to polymerase chain reaction (PCR) in life science. 

Enzymatic Bio-orthogonal Chemistry (EBC) is a way to introduce click chemistry to pharmaceutical industry and life science. In order to apply click chemistry in research or pharmaceutical industry, it is essential to introduce a clickable moiety to an interested target molecule. Through EBC,  clickable moieties are attached to target molecules specifically and quantitatively via enzymatic reactions, making molecular specific detection, imaging, labeling, conjugation and diagnosis possible. We are experts on EBC and want to help you achieve your goals in research or  drug design.  

EBC uses enzymes to specifically introduce clickable moiety to a target molecule. For example, clickable moiety can be first conjugated to a monosaccharides and then introduced by a glycosyltranseferases to target molecules. Because of the nature of enzymatic reactions, EBC is achieved under physiological conditions, therefore, it  is much more convenient, specific and has less side effects. 

Example 1. Imaging heparan sulfate in tissue culture

Using EBC, we are able to visualize heparan sulfate unequivocally for the first time. Heparan sulfate forms a net like structure therefore contributes the formation of extracellular matrix where cells can rest upon and grow and migrate.  Cells were revealed by  DAPI (4′,6-diamidino-2-phenylindole) staining.

Example 2. Imaging various glycans on HeLa cells

Using EBC,  we are able to image different  cellular glycans on cell surfaces and within cells. Different glycans exhibit strikingly different localizations. Core-1 O-glycan is shown  in B. Sialyl-Core-1 O-glycan is shown in C. Complex N-glycan is shown in F. Heparan sulfate is shown in G. O-GlcNAc is shown in H

Example 3. EBC labeling of hyaluronan (HA) for hyaluronidase assay

Low molecular hyaluronan (HA) was labeled by EBC and then digested with different hyaluronidases at indicated pH. HYAL1 is a lysosomal enzyme and is active when pH is below 5.5. HYAL2 and HYAL4 , distributed in extracellular matrix  to regulate the sizes of HA, are strictly active between pH 5.0 to 5.5, which is consistent to the fact that cancer cells become more metastatic at slight acidic conditions when these enzymes are active to break loose of HA in the matrix. SPAM1 (Sperm Adhesion Molecule 1), a hyaluronidase exclusively found at the tip of a sperm,  is widely active all across the pH range, which is consistent to its role of quickly breaking loose the HA surrounding an oocytes so that the sperm can fertilize the egg.  

We have variety ways to introduce a clickable moiety to a target molecule. If you have needs to detect, image or conjugate specific reporter molecules to interested target molecules, Bio-orthogonal is here to help you. Please contact:


2.     Wu, Z. L., and Ertelt, J. M. (2021) Assays for hyaluronidases and heparanase using nonreducing end fluorophore-labeled hyaluronan and heparan sulfate proteoglycan. Glycobiology 31, 1435-1443

3.     Wu, Z. L., and Ertelt, J. M. (2021) Fluorescent glycan fingerprinting of SARS2 spike proteins. Sci Rep 11, 20428

4.     Wu, Z. L., Whittaker, M., Ertelt, J. M., Person, A. D., and Kalabokis, V. (2020) Detecting substrate glycans of fucosyltransferases with fluorophore-conjugated fucose and methods for glycan electrophoresis. Glycobiology 30, 970-980

5.     Wu, Z. L., Person, A. D., Zou, Y., Burton, A. J., Singh, R., Burroughs, B., Fryxell, D., Tatge, T. J., Manning, T., Wu, G., Swift, K. A. D., and Kalabokis, V. (2020) Differential distribution of N- and O-Glycans and variable expression of sialyl-T antigen on HeLa cells-Revealed by direct fluorescent glycan imaging. Glycobiology 30, 454-462

6.     Wu, Z. L., Luo, A., Grill, A., Lao, T., Zou, Y., and Chen, Y. (2020) Fluorescent Detection of O-GlcNAc via Tandem Glycan Labeling. Bioconjug Chem 31, 2098- 2102

7.     Wu, Z. L., Person, A. D., Burton, A. J., Singh, R., Burroughs, B., Fryxell, D., Tatge, T. J., Manning, T., Wu, G., Swift, K. A. D., and Kalabokis, V. (2019) Direct fluorescent glycan labeling with recombinant sialyltransferases. Glycobiology 29, 750-754

8.     Wu, Z. L., Tatge, T. J., Grill, A. E., and Zou, Y. (2018) Detecting and Imaging O-GlcNAc Sites Using Glycosyltransferases: A Systematic Approach to Study O- GlcNAc. Cell Chem Biol 25, 1428-1435 e1423

9.     Wu, Z. L., Person, A. D., Anderson, M., Burroughs, B., Tatge, T., Khatri, K., Zou, Y., Wang, L., Geders, T., Zaia, J., and Sackstein, R. (2018) Imaging specific cellular glycan structures using glycosyltransferases via click chemistry. Glycobiology 28, 69-79

10.   Wu, Z. L., Huang, X., Ethen, C. M., Tatge, T., Pasek, M., and Zaia, J. (2017) Non-reducing end labeling of heparan sulfate via click chemistry and a high throughput ELISA assay for heparanase. Glycobiology 27, 518-524

12.   Wu, Z. L., Huang, X., Burton, A. J., and Swift, K. A. (2016) Probing sialoglycans on fetal bovine fetuin with azido-sugars using glycosyltransferases. Glycobiology 26, 329-334

14.   Wu, Z. L., Huang, X., Burton, A. J., and Swift, K. A. (2015) Glycoprotein labeling with click chemistry (GLCC) and carbohydrate detection. Carbohydrate research 412, 1-6

Leon Wu 

Leon has developed numerous novel enzymatic bio-orthogonal chemistry (EBC) based assays since 2012. He has applied EBC to labeling and conjugating purified proteins . He has also applied EBC to imaging various glycans on cell surface.

Assays developed at Bio-techne.pdf