SensoLyte® 520 Cathepsin K Assay – Long Wavelength

AnaSpec is pleased to announce the release of the industry's first and longest wavelength FRET based Cathepsin K assay, the SensoLyte® 520 Cathepsin K Assay Kit. Optimized for detecting Cathepsin K activity, this kit contains a novel internally quenched 5-FAM/QXL™ 520 FRET substrate. Upon cleavage of this FRET substrate, two separate fragments are generated resulting in the release of 5-FAM fluorescence. Fluorescence can be monitored at Ex/Em= 490/520 nm. Increase in fluorescence is proportional to the Cathepsin K activity. The SensoLyte® 520 Cathepsin K Assay Kit is AnaSpec's most specific assay kit in its catalog.

For biological samples containing mixed cathepsins, AnaSpec offers the SensoLyte® Rh110 Cathepsin K Assay Kit. Spectrally similar to the SensoLyte 520 assay kit, the Rh110 substrate is cleaved by Cathepsin L (if present in samples) at a faster rate than the FRET substrate provided in the 520 kit.

Both kits include long wavelength fluorescent dyes, 5-FAM and Rh110, that are subject to less interference by the autofluorescence of components in biological samples and test compounds.

Cathepsin K is a cysteine protease that plays a role in the degradation of protein components of the bone matrix during bone resorption.1 Produced by bone resorbing macrophages and synovial fibroblasts, Cathepsin K cleaves proteins such as collagen type I, collagen type II and osteonectin.2 It has potential as a drug target in autoimmune diseases and osteoporosis.3, 4


Catalog #

SensoLyte® Rh110 Cathepsin K Assay Kit *Fluorimetric*


SensoLyte® Rh110 Cathepsin
K Assay (Cat# AS-72152)




Ex/Em= 490/520 nm


Rh110 (Green)

Lowest Detection Limit

1 ng/ml

Kit size (96-well plate)

100 tests

Assay time

As short as 1h

Inhibitor screening

Related Products

SensoLyte® 520 Cathepsin S Activity Assay Kit (Ex/Em = 490 nm/520 nm)

SensoLyte® 440 Cathepsin S Activity Assay Kit (Ex/Em = 354 nm/442 nm)

SensoLyte® 390 Cathepsin D Activity Assay Kit (Ex/Em = 330 nm/390 nm)

Cathepsin Substrates, Inhibitors & Peptide

Full Listing of β-Amyloid GO™ Peptides

DHL™ β-amyloid (1-42) Sampler Kit

SensoLyte® a-Secretase Assay Kit

α-Synuclein recombinant human protein, HiLyte™ Fluor 488 labeled (Ex/Em = 490/520 nm)


1. Motyckova, G. et al. PNAS. 98 , 5798 (2001).
2. Hou, WS. et al. Am. J. Pathol. 159, 2167 (2001).
3. Skoumal, M. et al. Arthritis Res Ther. 7, 65 (2005).
4. Asagiri, M. et al. Science 319, 624 (2008).