Description
Principle of the assay: human Endostatin ELISA Kit was based on standard sandwich enzyme-linked immune-sorbent assay technology. A monoclonal antibody from human specific for Endostatin has been precoated onto 96-well plates. Standards(E.coli, H1154-S1335) and test samples are added to the wells, a biotinylated detection polyclonal antibody from goat specific for Endostatin is added subsequently and then followed by washing with PBS or TBS buffer. Avidin-Biotin-Peroxidase Complex was added and unbound conjugates were washed away with PBS or TBS buffer. HRP substrate TMB was used to visualize HRP enzymatic reaction. TMB was catalyzed by HRP to produce a blue color product that changed into yellow after adding acidic stop solution. The density of yellow is proportional to the human Endostatin amount of sample captured in plate.
Background: Endostatin is a naturally-occurring 20-kDa C-terminal fragment derived from type XVIII collagen. It is reported to serve as an anti-angiogenic agent, similar toangiostatin and thrombospondin. And It is produced by proteolytic cleavage of collagen XVIII, a member of the multiplexin family that is characterized by interruptions in the triple helix creating multiple domains, by proteases such as cathepsins. Using a genomic clone as a probe for fluorescence in situ hybridization, Endostatin was mapped the COL18A1 gene to 21q22.3. By immunoprecipitation analysis using membrane fractions of human mammary epithelial cells, It showed that endostatin specifically bound to cell surface nucleolin with high affinity. Blockage of nucleolin with neutralizing antibody or knockdown of nucleolin by RNA interference countered the antiendothelial activity of endostatin and abrogated its antiangiogenic and antitumor activity in vivo