Antibody-β-glucuronidase Conjugate

As a professional service provider in antibody-drug conjugates (ADCs) design and preparation, Creative Biolabs offers comprehensive and reliable antibody-directed enzyme prodrug therapy (ADEPT) development services using Antibody-β-glucuronidase conjugate combining with a potential prodrug for targeted immunotherapy.

β-glucuronidase

β-glucuronidases, which is encoded by the GUSB gene, is one of the members of glycosidase family. It exerts its function by catalyzing the breakdown of complex carbohydrates. Human β-glucuronidase is a 78 kDa monomer which is formed after the proteolysis of 80 kDa monomer. Its homotetramer is a stable form existing in the lysosome. In general, it is mainly located in the lysosome and catalyze the hydrolysis of β-D-glucuronic acid residues from the non-reducing end of mucopolysaccharides (glycosaminoglycans) such as heparan sulfate. In the gut, β-glucuronidase could transform conjugated bilirubin into the unconjugated form for reabsorption.

Fig.1 Stereo ribbon diagram of human beta-glucuronidase. In the tetramer, the four monomers are colored in red, blue, green and violet respectively. (Jain, 1996)

MOA of β-glucuronidase

Glycosidases often performs its hydrolysis by two acidic residues, namely Glu540 and Glu451. Besides, the tyrosine residue Tyr504 also contributes to the catalysis function of glycosidases. Mutation of any of these three residues could lead to a significant decrease in enzymatic activity. In addition to the above residues, a conserved asparagine residue (Asn450) has been demonstrated to stabilize the substrate through the action of a hydrogen bond at the 2-hydroxyl group of the sugar substrate. The prodrug, such as phenol mustard glucuronide, can be activated by β-glucuronidase hydrolysis and thus yield the parent drug phenol mustard.

Fig.2 Glucuronide prodrugs of paclitaxel 1-3. (Tranoy-Opalinski, 2014)

Antibody-β-glucuronidase Conjugate-based ADEPT

β-glucuronidases is used as an effective enzyme in the ADEPT development actively. As one of the most suitable monoclonal antibody, scFv mAb can be applied to promote the treatment of cancer in ADEPT. For example, a single-chain antibody-enzyme fusion protein composed of the human anti-Ep-CAM scFv antibody C28 and the human lysosomal enzyme GUS is used for the treatment of cancer. Generally, the fusion protein is expressed as a tetramer in the supernatant. Studies have shown that fusion protein could retain at least 50% enzymatic activity and bind specifically to Ep-CAM-expressing cells. In addition, it is also able to convert the glucuronide-prodrug DOX-GA3. And 10% of C28-GUSh expressing cells suffice to accomplish uptake of doxorubicin into all cells in the population.

Experienced scientists from Creative Biolabs provide custom ADEPT development service by using antibody-β-glucuronidases conjugate. Our high-quality services and products will contribute greatly to the success of your projects. We also provide other various services regarding ADEPT development. Please contact us for more information and a detailed quote.

References

1. Jain, S.; Drendel, et al. Structure of human β-glucuronidase reveals candidate lysosomal targeting and active-site motifs. Nature Structural and Molecular Biology. 1996, 3(4), 375.
2. Tranoy-Opalinski, I.; et al. β-Glucuronidase-responsive prodrugs for selective cancer chemotherapy: an update. European journal of medicinal chemistry. 2014, 74, 302-313.