ADAMTS13 (A Disintegrin-like and Metalloprotease with Thrombospondin type-1 motifs 13) is a metalloproteinase that is primarily synthesized in liver cells and secreted into blood circulation. ADAMTS13 specifically cleaves von Willebrand factor (vWF) at the Tyr1605-Met1606 peptide bond. vWF is a multimeric glycoprotein that mediates adhesion and aggregation of platelets. ADAMTS13 is essential for preventing platelet aggregation in the circulation. Deficiency of plasma ADAMTS13 activity may lead to thrombotic thrombocytopenic purpur (TTP), a potentially lethal syndrome characterized by the formation of VWF-platelet-rich thrombi in the arterioles and capillaries. Studies have shown that ADAMTs13 is also involved in angiogenesis, inflammation, atherosclerosis, and liver cirrhosis. Measurement of ADAMTS13 activity in plasma has been used for supporting diagnosis of acute TTP.
The SensoLyte® 520 ADAMTS13 Assay Kit employs an internally quenched vWF73 FRET peptide substrate for the detection of enzyme activity. This substrate contains a novel 5-FAM/QXL® 520 FRET pair. ADAMTS13 cleaves this FRET substrate into two separate fragments resulting in the release of 5-FAM fluorescence, which can be monitored at Ex/Em= 490/520 nm. The long wavelength fluorescence of 5-FAM is less interfered by the autofluorescence of components in biological samples.