Cathepsin B ELISA Kit (CTSB)


Human cathepsin B ELISA kit is a protocol intended for detecting in vitro quantitative amounts of cathepsin B (CTSB) in human serum, plasma, biological fluids and tissue homogenates. This assay has a minimum detection limit of 0.094 ng/ml.


Cathepsin B belongs to family of lysosomal cysteine proteases and these are known to play vital functions during intracellular proteolysis. It can be synthesized on the rough endoplasmic reticulum as a pre-proenzyme that is 339 amino acid in length and it also possess a signal peptide that is 17 amino acids, this pro-cathepsin B of 43/46 kDa can then be transported to the Golgi apparatus where cathepsin B is formed. The mature protein consists of a heavy chain of 25-26 kDa and a light chain that is 5kDa which are linked by a dimer of disulphide.

Cathepsin B can enhance the activity of other protease such as; urokinase, cathepsin D and matrix metalloproteinase, therefore giving it an important role in intercellular communication disruption, reducing protease inhibitor expression and in the proteolysis of extracellular matrix components. There are also evidence for its involvement in cannibalism and autophagy, this is advantageous in specific immune resistance and tumor malignancy. Upregulation has also be discovered in pre-malignant lesions and various other pathological conditions such as cancers. It is often proposed as a potentially effective biomarker for a number of cancers and its overexpression has been correlated with many metastatic and invasive cancers.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • One 96-Well Plate: Pre-coated with anti CTSB antibody.
  • Standards: Concentrations 0, 0.156, 0.312, 0.625, 1.25, 2.5, 5.0, 10 ng/ml, made up from lyophilized recombinant.
  • Sample/Standard Dilution Buffer.
  • Biotinylated-Labelled Antibody.
  • Antibody Dilution Buffer.
  • HRP-Streptavidin Conjugate (SABC).
  • SABC Dilution Buffer.
  • TMB Substrate.
  • Wash Buffer (25x).
  • Plate Sealer.
  • Product Instructions.


The minimum detection sensitivity level of cathepsin-B (CTSB) using this cathepsin-B ELISA kit was 0.094 ng/ml. The dynamic assay range for this kit is 0.156 – 10.0 ng/ml.


– Specificity: Highly specific for CTSB, no cross reactivity or interference between CTSB and analogues was detected.
– Recovery: Serum (88 – 105%), EDTA Plasma (91 – 99%), Heparin Plasma (90 – 95%).
– Linearity: Serum (89 – 105%), EDTA Plasma (84 – 95%), Heparin Plasma (81 – 96%).
– Precison Intra-Assay: CV < 8%.
– Precison Inter-Assay: CV < 10%.
– Stability: Less than 10%.


  1. Specialized roles for cysteine cathepsins in health and disease. J Clin Invest. (2010) 120 (10): 3421-31. Review. Reiser J., et al.
  2. Molecular regulation of human cathepsin B: implication in pathologies. Biol Chem. (2003) 384 (6): 845-54. Review. Yan S. and Sloane B.F.
  3. Cell surface complex of cathepsin B/annexin II tetramer in malignant progression. Biochim Biophys Acta. (2000) 1477 (1-2): 215-30. Review. Mai J., et al.
  4. Inhibitors of cathepsin B. Curr Med Chem. (2006) 13 (19): 2309-27. Review. Frlan R. and Gobec S.
  5. Macrophage derived cystatin B/cathepsin B in HIV replication and neuropathogenesis. Curr HIV Res. (2014) 12 (2): 111-20. Review. Rivera L.E., et al.


  • Full Name: Cathepsin B ELISA Kit (CTSB)
  • Reactivity: Human
  • Sample Type: Plasma, Serum, Biological Fluids, Tissue Homogenates
  • Sensitivity: 0.094 ng/ml


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