• Nature

  • Source

    Escherichia coli
  • Amino Acid Sequence
    • Accession
    • Species

    • Molecular weight

      35 kDa
    • Amino acids

      19 to 215


Our Abpromise guarantee covers the use of ab134431 in the following tested applications.

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

  • Biological activity

    The specific activity of activated ab134431 is > 1 U/mg. One U is the activity that hydrolyses 1 µmole substrate BOC-Phe-Arg-7- amido-4-methylcoumarin per min at 37°C in 2.5 mM EDTA, 5 mM DTT, 50 mM MES, pH 5.5.
  • Applications

    Functional Studies

    Inhibition Assay


  • Purity

    > 95 % SDS-PAGE.

  • Form

  • Additional notes

    Activation: Procathepsin K can be activated by adjusting the procathepsin K solution to pH 4.0 with an equal volume of 100 mM NaAc pH 3.9, 10 mM DTT, 5 mM EDTA followed by an incubation for approximately 40 minutes at room temperature. After activation ab134431 is rather unstable. If the activated enzyme is not used immediately, it is recommended to add MMTS (1 mM final concentration) and to quick-freeze the sample in liquid nitrogen or dry ice. For activity measurements L-cysteine must then be added to restore the active conformation of the enzyme.

    Inhibitors: Cathepsin K is inhibited by leupeptin (IC50: 70 nM), E-64 (IC50: 5 nM), and cystatin.

    Activity: Cathepsin K activity can be measured in assay buffer consisting of 50 mM MES pH 5.5, 2,5 mM EDTA, 5 mM DTT. If the activated enzyme was irreversible inhibited by MMTS the enzyme solution should first be adjusted to 3 mM L-cysteine and kept on ice until use. The assay is initiated by addition of substrate (benzyloxycarbonyl-phenylalanine–arginine-7-amido-4 methylcoumarin) to a final concentration of 100 µM (stock solution 10 mM in DMSO). Activity is monitored by the increase in fluorescence accompanying release of the product 7-amino-4-methylcoumarin (AMC) (McQueney et al., 1997). Excitation and emission are at 360/460 nm, respectively 7-amino-4 methylcoumarin (AMC) (10 mM) is used as standard.

  • Concentration information loading...

Preparation and Storage

  • Stability and Storage

    Shipped on dry ice. Upon delivery aliquot and store at -80ºC. Avoid freeze / thaw cycles.

    pH: 8.00
    Constituents: 0.395% Tris HCl, 2.92% Sodium chloride

    This product is an active protein and may elicit a biological response in vivo, handle with caution.

General Info

  • Alternative names

    • Cathepsin K
    • Cathepsin O
    • Cathepsin O1
    • Cathepsin O2
    • Cathepsin X
    • Ctsk
    • CTSO
    • CTSO2
    • PKND
    • PYCD
    see all
  • Function

    Closely involved in osteoclastic bone resorption and may participate partially in the disorder of bone remodeling. Displays potent endoprotease activity against fibrinogen at acid pH. May play an important role in extracellular matrix degradation.
  • Tissue specificity

    Predominantly expressed in osteclasts (bones).
  • Involvement in disease

    Defects in CTSK are the cause of pycnodysostosis (PKND) [MIM:265800]. PKND is an autosomal recessive osteochondrodysplasia characterized by osteosclerosis and short stature.
  • Sequence similarities

    Belongs to the peptidase C1 family.
  • Cellular localization

  • Information by UniProt


  • SDS-PAGE analysis of ab134431 (2 µg)


ab134431 has not yet been referenced specifically in any publications.

Customer reviews and Q&As


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