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}

	SensoLyte® 520 Cathepsin K Assay (Cat# 72151)	SensoLyte® Rh110 Cathepsin K Assay (Cat# 72152)
Read-out	Fluorimetric, FRET based (5-FAM/QXL™ 520)	Fluorimetric
Wavelengths	Ex/Em= 490/520 nm	Ex/Em= 490/520 nm
Fluorophore	5-FAM (Green)	Rh110 (Green)
Lowest Detection Limit	10 ng/ml	1 ng/ml
Kit size (96-well plate)	100 tests	100 tests
Assay time	As short as 1h	As short as 1h
Inhibitor screening

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