Adding to a broad collection of long wavelength FRET protease assay kits, AnaSpec has introduced the SensoLyte™ 520 Cathepsin S Assay Kit.
The SensoLyte™ 520 Cathepsin S Activity Assay Kit is a homogeneous assay that can be used to detect the activity of Cathepsin S in biological samples or in purified enzyme preparations. A unique long wavelength 5-FAM/QXL™ 520 FRET peptide substrate is used in this kit. When active Cathepsin S cleaves this FRET substrate, it results in an increase of 5-FAM fluorescence, which can be monitored at Ex/Em = 490 nm/520 nm. The long wavelength fluorescence of 5-FAM is less interfered by the autofluorescence of cell components and test compounds.

Cathepsin S is a lysosomal cysteine proteinase of the papain family. It plays a major role in the degradation of the invariant peptide chain associated with the major histocompatibility complex and thus affects antigen presentation.1, 2 Since antigen presentation is the key to immune response, Cathepsin S has been validated as an immunomodulatory target.3, 4 Cathepsin S is also involved in several pathologies including atherosclerosis, cancer, obesity and their associated diseases.5-9

AnaSpec also provides the SensoLyte 440 Cathespsin S Activity Assay Kit. The substrate used in this kit releases the AMC (7-amino-4-methylcoumarin) fluorophore upon Cathepsin S cleavage. AMC has bright blue fluorescence that can be detected with excitation at 354 nm and emission at 442 nm.

About AnaSpec, Inc.
AnaSpec, Inc. is a leading provider of integrated proteomics solutions to pharmaceutical, biotech, and academic research institutions throughout the world. With a vision for innovation through synergy, AnaSpec focuses on three core technologies: peptides, detection reagents (dyes, assay kits, & antibodies), and combinatorial chemistry.

References:
1. Honey, K and AY. Rudensky, Nat. Rev. Immunol. 3, 472 (2003)
2. Hsieh, CS. et al, J. Immunol. 168, 2618 (2002)
3. Gupta, S. et al, Expert Opin. Ther. Targets 12, 291 (2008)
4. Thurmond, RL et al, Curr. Opin. Investi.g Drugs 6, 473 (2005)
5. Sukhova, GK. et al, J. Clin. Invest. 111, 897 (2003)
6. Taleb, S. et al, FASEB J. 19, 1540 (2005)
7. Liu, J. et al, Atherosclerosis 186, 411 (2006)
8. Taleb, S. et al, J. Clin. Endocrinol. Metab. 91, 1042 (2006)
9. Wang, B. et al, J. Biol. Chem. 281, 6020 (2006).