Amino Acids (AA)

Copeptin is a human protein that is found in the blood and urine. It functions as a competitive inhibitor of lysine-specific proteases, such as cathepsin D, elastase, and trypsin. Copeptin binds to the active site of these enzymes and prevents them from cleaving their substrates. Copeptin is also an antigen used in immunohistochemistry with an antibody against it for use in detection of various cancers. The biotinylated form of copeptin can be used for binding to avidin or streptavidin coated plates or antibodies (e.g., peroxidase-conjugated antibody) for use in enzyme-linked immunosorbent assays (ELISA). Copeptin binds to primary antibodies raised against it by the immune system, which are then detected using fluorescent secondary antibodies or peroxidase-conjugated antibodies.