Human Cathepsin S ELISA Kit

Kit Components

 1. Recombinant Human Cathepsin S standard: 2 vials

 2. One 96-well plate precoated with anti- Human Cathepsin S Ab

 3. Sample diluent buffer: 12 mL - 1

 4. Detection antibody: 130 µL, dilution 1:100

 5. Streptavidin-HRP: 130 µL, dilution 1:100

 6. Antibody diluent buffer: 12 mL x1   

 7. Streptavidin-HRP diluent buffer: 12 mL x1

 8. TMB developing agent: 10 mL x1

9. Stop solution: 10 mL x1.

10. Washing solution (20x): 25 mL x1.

Background

The cathepsins are a group of lysosomal proteases that are active in acidic environments and play an important role in protein degradation. Currently, 11 human cathepsins (B, C, F, H, K, L, O, S, V, W and X) have been shown to have broad substrate specificity. For example, Cathepsins A and G are serine proteases and cathepsins D and E are aspartic proteases. Cathepsins are synthesized as inactive proenzymes and processed to become mature and active enzymes. Cathepsin S is a lysosomal cysteine protease of the papain family. The full-length human Cathepsin S is a 331 amino acid (aa) preproenzyme consisting of a signal peptide (residues 1-16), a proregion (residues 17-114), and the mature enzyme (residues 115-331). Cathepsin S is expressed by antigen presenting cells including macrophages, B-lymphocytes, dendritic cells and microglia. It is also expressed in some epithelial cells.

Cathepsin S plays a critical role in antigen presentation. In general, MHC class II selects small peptide fragments for presentation on the surface of the antigen-presenting immune cells. cathepsin S participates in a degradation of polypeptide li that prevents loading the antigen into the complex. This degradation occurs in the lysosome and it is a part of normal MHC II folding process. In addition, Cathepsin S cleaves a variety of extracellular matrix (ECM) proteins such as laminin, fibronectin elastin, osteocalcin and some collagens. It also cleaves chondroitin sulfate, heparan sulfate and proteoglycans of the basal membrane. Cathepsin S exhibits its activity in blood vessels permeability and angiogenesis due to its elastolytic and collagenolytic activities. Cathepsin S has been implicated in the pathogenesis of several diseases such as Alzheimer’s disease and degenerative disorders associated with the cells of the mononuclear phagocytic system.