Granzymes are a family of structurally related serine proteases. They are stored within the cytotoxic granules of cytotoxic lymphocytes. Granzymes are known to induce target-cell apoptosis. They have the faculty to initiate cell death once entered the target cells (viral or tumor cells). Granzyme A and B are the most abundantly studied.
Granzyme B is a serine protease mostly secreted by cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. It is one of the major mediators of caspase-dependent apoptosis. Recent studies showed that Granzyme B can also be secreted by various non-cytotoxic cells and involved in degradation of extracellular matrix proteins thereby inducing inflammation and impairing wound healing. Thus, if intracellular activity of Granzyme B is mainly related to apoptosis, its extracellular activity has been linked to roles in arthritis, vascular pathologies, and other diseases.
The SensoLyte® 520 Granzyme B Assay Kit provides a convenient assay for screening of enzyme inhibitors or for continuous assay of Granzyme B activity using a novel internally quenched 5-FAM/QXL®FRET substrate. Upon cleavage by Granzyme B, the FRET substrate will be separated into two fragments resulting in release of 5-FAM fluorescence which can be monitored at excitation /emission= 490 nm/520 nm. The kit can be used to detect the activity of Granzyme B enzyme in biological samples and purified enzyme preparations. This assay can detect as low as 0.1 ng/mL active granzyme B.