Anaspec has released the Sensolyte 520 Cathepsin B Fret-based activity assay kit, which can be used for measuring Cathepsin B activity and for screening Cathepsin B inhibitors.
The substrate employed in this kit is a peptide sequence containing the QXL 520/Hilyte Fluor 488 Fret pair.
In the intact sequence, the fluorescence of Hilyte Fluor 488 is quenched by QXL 520.
Upon recognition and cleavage by Cathepsin B, the peptide is cleaved into two separate fragments, resulting in the release of Hilyte Fluor 488 fluorescence.
Fluorescence can be continuously monitored at the green emission range of 520m (Ex=488nm).
The long wavelength fluorescence and pH-independent properties of Hilyte Fluor 488 mean less interference by the auto-fluorescence of cellular components and test compounds and the ability to measure Cathepsin B activity at its optimal low pH.
Cathepsin B is a cysteine proteinase belonging to the papain family with broad exo- and endo-peptidase activity.
The over-expression of Cathepsin B has been shown to correlate with metastatic potential and the enzyme is implicated in the ability of tumour cells to invade the extracellular matrix and to metastasise to secondary sites.
Cathepsin B levels are also elevated in a variety of neurological disorders, including Alzheimer's disease.
