• Product name
    Cathepsin S Activity Assay Kit (Fluorometric)
    See all Cathepsin S kits
  • Sample type
    Tissue Extracts, Cell Lysate
  • Assay type
    Enzyme 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.


  • Storage instructions
    Store at -20°C. Please refer to protocols.
  • Components Identifier 100 tests
    CS Cell Lysis Buffer WM 1 x 25ml
    CS Inhibitor (1 mM) Red 1 x 20µl
    CS Reaction Buffer NM 1 x 5ml
    CS Substrate Ac-VVR-AFC (10 mM) Brown 1 x 200µl
  • Research areas
  • Relevance
    The 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 localization
  • Alternative names
    • CathepsinS
    • CTSS
    • MGC3886

Associated products


  • 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).



This product has been referenced in:
  • Zhang J  et al. Palmitate impairs angiogenesis via suppression of cathepsin activity. Mol Med Rep 15:3644-3650 (2017). Read more (PubMed: 28440480) »
  • Hsin MC  et al. Hispolon suppresses metastasis via autophagic degradation of cathepsin S in cervical cancer cells. Cell Death Dis 8:e3089 (2017). Read more (PubMed: 28981104) »

See all 5 Publications for this product

Customer reviews and Q&As

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.


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