• Product nameCathepsin S Activity Assay Kit (Fluorometric)
    See all Cathepsin S kits
  • Tests
    100 x 1 assay
  • Sample type
    Tissue Extracts, Cell Lysate
  • Assay typeEnzyme activity
  • Assay time
    2h 00m
  • Product overview

    Cathepsin S Activity Assay Kit (ab65307) is a fluorescence-based assay that utilizes the preferred cathepsin-S substrate sequence VVR labeled with AFC (amino-4-trifluoromethyl coumarin). Cell lysates or other samples that contain cathepsin-S will cleave the synthetic substrate VVR-AFC to release free AFC. The released AFC can easily be quantified using a fluorometer or fluorescence plate reader.
    Visit our FAQs page for tips and troubleshooting.

  • Notes

    Apoptosis can be mediated by mechanisms other than the traditional caspase-mediated cleavage cascade. There is growing recognition that alternative proteolytic enzymes such as the lysosomal cathepsin proteases may initiate or propagate proapoptotic signals. Cathepsins are lysosomal enzymes that are also used as sensitive markers in various toxicological investigations.

  • Tested applicationsSuitable for: Functional Studiesmore details


  • RelevanceThe cathepsin family of proteases contains several diverse classes of enzymes. The cysteine protease class comprises cathepsin B, H, K, L, O, and S. The aspartyl protease class contains cathepsin D and E. Cathepsin G belongs to the serine protease class. Cathepsins are involved in various cellular events such as peptide biosynthesis, protein degradation, and apoptosis. Cathepsin S has been shown to be able to function as an elastase over a broad pH range in alveolar macrophages.
  • Cellular localizationLysosome
  • Alternative names
    • CathepsinS
    • CTSS
    • MGC3886

Associated products


Our Abpromise guarantee covers the use of ab65307 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

Application Abreviews Notes
Functional Studies Use at an assay dependent dilution.

Cathepsin S Activity Assay Kit (Fluorometric) images

  • Cathepsin S Activity measured in tissue lysates (each with protein concentration of 4 mg/mL) after 1 hour of incubation.

  • Cathepsin S Activity measured in cell lysates (each with cells concentration of 4e7 cells/mL) after 1 hour of incubation with and without inhibitor (I).


References for Cathepsin S Activity Assay Kit (Fluorometric) (ab65307)

This product has been referenced in:
  • Chiang L  et al. Rab27b regulates exocytosis of secretory vesicles in acinar epithelial cells from the lacrimal gland. Am J Physiol Cell Physiol 301:C507-21 (2011). Read more (PubMed: 21525430) »

See 1 Publication for this product

Product Wall

I can confirm that the use of conditioned medium does not change the Cathepsin S assay in any way. Typically the conditioned medium is removed and retained and the cells are lysed to assay for Cathepsin activity. The Cathepsin activity in the medium is...

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We do not recommend to prepare one lysate to use with ab65302, ab65306 and ab65307.
It is important to prepare separate lysates for each kit, using the specific lysis buffer provided. This is because the cathepsins have very specific pH and other c...

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The lab let me know that they do not have any additional tips for tissue processing other than the ones we mention on the FAQ site.

12. How should tissue be prepared for the kits?

Samples should be completely homogenized, pr...

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Yes you can use cell lysates or tissue extract samples with this kit.

This kit does not come with a positive control.