Alkaline Phosphatase: IHC Dephosphorylation for Rapid Cancer Detection

Abstract

According to the American Cancer Society, one third of women and half of men risk developing cancer in the United States. This results in a growing, critical effect on both social and economic aspects of society. Fortunately, researchers are developing simple, accurate tests for cancer detection. Many immunohistochemistry (IHC) assays use alkaline phosphatase (AP) to detect in‐vitro cancers. IHC assays use antibody‐enzyme conjugates that pair with primary antibodies specific to antigens on the surface of cancer cells. As the catalyzing enzyme, AP removes a phosphate from a substrate resulting in a color precipitate localized to cells expressing the specific cancer antigen. AP is a homo‐dimer phosphomonoesterase containing two Zn atoms and one Mg atom in each subunit; one Zn atom and the Mg atom maintain structure, and the other Zn atom works with Ser102 to remove a phosphate. The critical amino acids in AP's active site create the electrostatic environment needed for Ser102 to begin dephosphorylation. AP has many in‐vivo functions and laboratory applications, including calcification of cartilage as well as the synthesis, sequencing, and labeling of DNA. The Ironwood Ridge High School SMART (Students Modeling A Research Topic) Team has modeled AP, using 3D printing technology. By studying AP's structure and function, we are able to visualize its role as a chemical detector. Sponsored by a grant from NIH‐SEPA.