Antibody-alkaline Phosphatase Conjugate

Creative Biolabs is one of the well-recognized experts in the field of antibody-directed enzyme prodrug therapy (ADEPT) development. With years of experience, our scientists offer high-quality antibody development and antibody-enzyme conjugation services to meet clients’ demands precisely. Particularly, we provide antibody-alkaline phosphatase conjugate service for targeted immunotherapy based on our optimized enzyme and antibody conjugation strategies.

Alkaline Phosphatase

Alkaline phosphatase (ALP) is a homodimeric protein enzyme. Each monomer consists of five cysteine residues, two zinc atoms, and one magnesium atom which is essential to its catalytic function. It performs its optimal activity when in alkaline pH conditions. ALP plays a role in dephosphorylating of compounds. The enzyme is found in a wide range of species including prokaryotes and eukaryotes alike. It harbors different structural forms suitable to the environment but possessing the same normal function. ALP is found in the periplasmic space of E. coli bacteria. This enzyme has thermal stability and maximum activity at high pH. In humans, it is identified in many forms according to its origin within the body. It is involved in the metabolism within the liver and development within the skeleton. Because of it widely ex in different areas, its concentration in the bloodstream is used as a biomarker in helping determine diagnoses such as hepatitis or osteomalacia.

Crystal structure of alkaline phosphatase from E. coli (A) and human placenta (B) highlighting the structural similarity between bacterial and mammalian forms of the enzyme. Monomer subunits are colored differently to highlight the dimeric nature of the enzymes. Fig.1 Crystal structure of alkaline phosphatase from E. coli (A) and human placenta (B) highlighting the structural similarity between bacterial and mammalian forms of the enzyme. Monomer subunits are colored differently to highlight the dimeric nature of the enzymes. (Igunnu, 2011)

MOA of Alkaline Phosphatase

Alkaline phosphatase enzyme catalyzes the cleavage of prodrug doxorubicin phosphate and thus yields an effective drug Doxorubicin, which is a chemotherapy medication used to treat cancer. It inhibits the moving of topoisomerase II, an enzyme which relaxes supercoils during DNA transcription. Doxorubicin can stabilize the topoisomerase II complex after it broke the DNA chain for replication.

Antibody-alkaline Phosphatase Conjugate-based ADEPT

The use of antibody-enzyme conjugates directed at tumor-associated antigens to achieve site-specific activation of prodrugs has attracted considerable interest since the concept was first described in 1987. Alkaline phosphatase is one of the enzymes used in ADEPT, which has been demonstrated has the potential to treat the colorectal tumor. In addition, pretreatment of the H2981 cells with L6-alkaline phosphatase (L6-AP), a monoclonal antibody conjugate that could bind to cell surface antigens, greatly strengthen the cytotoxic effects of prodrug POMP in an immunologically specific manner. However, antitumor activity was observed in animals receiving L6-AP-ADEPT 48hr prior to POMP administration. Thus, the level of activity is greater than that of given the drug alone.

Schematic presentation of biological functions of RCAS1. Fig.2 Schematic diagram of the principle of ADEPT. (Sharma, 2005)

Creative Biolabs is committed to helping clients develop antibody-alkaline phosphatase conjugate-based ADEPT. Our customarily tailored services and high-quality linker products will contribute greatly to the success of your projects. Creative Biolabs also provides other various services regarding ADEPT development. Please feel free to contact us for more information.


  1. Igunnu, A.; et al. Distinct metal ion requirements for the phosphomonoesterase and phosphodiesterase activities of calf intestinal alkaline phosphatase. The open biochemistry journal. 2011, 5, 67.
  2. Sharma, S. K.; et al. Sustained tumor regression of human colorectal cancer xenografts using a multifunctional mannosylated fusion protein in antibody-directed enzyme prodrug therapy. Clinical cancer research. 2005, 11(2), 814-825.

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