Recombinant Human Kallikrein 4/Prostase Protein, CF


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Product Details

Reactivity HuSpecies Glossary
Applications Enzyme Activity

Order Details

Recombinant Human Kallikrein 4/Prostase Protein, CF Summary

Details of Functionality
Measured by its ability to cleave the fluorogenic peptide substrate Boc-VPR-AMC (Catalog # ES011). The specific activity is >250 pmol/min/µg, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Kallikrein 4/Prostase/EMSP1 protein
Ser27-Ser254, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Ser27 & Ser29
Structure / Form
Pro form
Protein/Peptide Type
Recombinant Enzymes
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
Endotoxin Note
<1.0 EU per 1 μg of the protein by the LAL method.


  • Enzyme Activity
Theoretical MW
26 kDa.
Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
33 kDa, reducing conditions
Read Publications using
1719-SE in the following applications:

Packaging, Storage & Formulations

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.
Lyophilized from a 0.2 μm filtered solution in Tris and NaCl.
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
Reconstitution Instructions
Reconstitute at 200 μg/mL in sterile 50 mM Tris, 10 mM CaCl2 and 150 mM NaCl, pH 7.5.
Assay Procedure
  • Activation Buffer: 50 mM Tris, 10 mM CaCl2, 150 mM NaCl, pH 7.5 (TCN)
  • Assay Buffer: 50 mM Tris, pH 9.0
  • Recombinant Human Kallikrein 4/Prostase/EMSP1 (rhKLK4) (Catalog # 1719-SE)
  • Bacterial Thermolysin (Thermolysin) (Catalog # 3097-ZN)
  • 1,10 Phenanthroline (Sigma, Catalog # 320056), 0.6 M stock in DMSO
  • Substrate: BOC-Val-Pro-Arg-AMC (Catalog # ES011) , 90 mM Stock in DMSO
  • F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
  • Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent
  1. Dilute rhKLK4 to 200 µg/mL in Activation Buffer.
  2. Dilute Thermolysin to 2 µg/mL in Activation Buffer.
  3. Combine equal volumes diluted rhKLK4 and Thermolysin and incubate at 37 °C for 2 hours to activate.
  4. Stop the reaction with 1,10 Phenanthroline at a final concentration of 10 mM.
  5. Dilute activated rhKLK4 to 2 ng/µL in Assay Buffer.
  6. Dilute Substrate to 200 µM in Assay Buffer.
  7. Load 50 µL of the 2 ng/μL rhKLK4 in a plate and start the reaction by adding 50 μL of 200 μM Substrate. Include a Substrate Blank containing 50 µL Assay Buffer and 50 µL of 200 µM Substrate without any rhKLK4.
  8. Read at excitation and emission wavelengths of 380 nm and 460 nm (top read), respectively, in kinetic mode for 5 minutes.
  9. Calculate specific activity:

     Specific Activity (pmol/min/µg) =

Adjusted Vmax* (RFU/min) x Conversion Factor** (pmol/RFU)
amount of enzyme (µg)

     *Adjusted for Substrate Blank
     **Derived using calibration standard 7-Amino, 4-Methyl Coumarin (Sigma, Catalog # A-9891).

Per Well:
  • rhKLK4: 0.100 µg
  • Substrate: 100 µM


This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant Human Kallikrein 4/Prostase Protein, CF

  • AI2A1
  • ARM1
  • EC 3.4.21
  • EC 3.4.21.-
  • EMSP
  • EMSP1
  • EMSP1MGC116827
  • Enamel matrix serine proteinase 1
  • kallikrein 4 (prostase, enamel matrix, prostate)
  • Kallikrein 4
  • kallikrein-4
  • Kallikrein-like protein 1
  • kallikrein-related peptidase 4
  • KLK4
  • KLK-L1MGC116828
  • Prostase
  • PRSS17enamel matrix serine protease 1
  • PSTSandrogen-regulated message 1
  • Serine protease 17


Kallikrein 4 (KLK4), also known as prostase or enamel matrix serine protease 1 (EMSP1), is a serine protease of the human tissue kallikrein gene family (1). Among normal tissues, human KLK4 is specifically expressed in the prostate (2). It is over-expressed in prostate cancer and this expression is regulated by hormones including androgens, esterogen and progesterone (3). rhKLK4 readily activates pro-KLK3/PSA and pro-urokinase type plasminogen activator (uPA), indicating it may initiate events involving PSA and uPA in either normal or abnormal processes (4). KLK4 may have additional roles such as functioning as one of the two major enamel proteases identified that process enamel matrix proteins (5). In addition to being a secreted enzyme, it is also a nuclear protein (3, 6). The deduced amino acid sequence of human KLK4 consists of a signal peptide, a short pro region and a mature/active enzyme. rhKLK4 can be activated in vitro by thermolysin, a zinc protease. The peptidase activity can be inhibited by AEBSF (R&D Systems, Catalog # EI001), a general serine protease inhibitor.

  1. Yousef, G.M. and E.P. Diamandis (2001) Endocrine Rev. 22:184.
  2. Nelson, P.S. et al. (1999) Proc. Natl. Acad. Sci. USA 96:3114.
  3. Xi, Z. et al. (2004) Cancer Res. 64:2365.
  4. Takayama, T.K. et al. (2001) Biochemistry 40:15341.
  5. Simmer, J.P. and J.C. Hu (2002) Connect Tissue Res. 43:441.
  6. Ryu, O.H. et al. (2002) Eur. J. Oral. Sci. 110:358.

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Publications for Kallikrein 4/Prostase/EMSP1 (1719-SE)(6)

We have publications tested in 2 confirmed species: Human, Rat.

We have publications tested in 3 applications: Bioassay, Enzyme Assay, Surface Plasmon Resonance.

Filter By Application
Enzyme Assay
Surface Plasmon Resonance
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Showing Publications 1 - 6 of 6.
Publications using 1719-SE Applications Species
B Chan, IC Cheng, J Rozita, I Gorshteyn, Y Huang, I Shaffer, C Chang, W Li, J Lytton, P Den Besten, Y Zhang Sodium/(calcium + potassium) exchanger NCKX4 optimizes KLK4 activity in the enamel matrix microenvironment to regulate ECM modeling Frontiers in Physiology, 2023-02-06;14(0):1116091. 2023-02-06 [PMID: 36814474] (Bioassay, Human) Bioassay Human
R Williams, VA Perez, JE Mangum, MJ Hubbard Pathogenesis of Molar Hypomineralisation: Hypomineralised 6-Year Molars Contain Traces of Fetal Serum Albumin Front Physiol, 2020-06-12;11(0):619. 2020-06-12 [PMID: 32595522] (Bioassay, Human, Rat) Bioassay Human, Rat
Kantyka T, Fischer J, Wu Z, Declercq W, Reiss K, Schroder J, Meyer-Hoffert U Inhibition of kallikrein-related peptidases by the serine protease inhibitor of Kazal-type 6. Peptides, 2011-03-23;32(6):1187-92. 2011-03-23 [PMID: 21439340] (Human) Human
Sexton DJ, Chen T, Martik D, Kuzmic P, Kuang G, Chen J, Nixon AE, Zuraw BL, Forteza RM, Abraham WM, Wood CR Specific inhibition of tissue kallikrein 1 with a human monoclonal antibody reveals a potential role in airway diseases. Biochem. J., 2009-08-13;422(2):383-92. 2009-08-13 [PMID: 19527222] (Surface Plasmon Resonance, Human) Surface Plasmon Resonance Human
Mukai S, Fukushima T, Naka D, Tanaka H, Osada Y, Kataoka H Activation of hepatocyte growth factor activator zymogen (pro-HGFA) by human kallikrein 1-related peptidases. FEBS J., 2008-01-25;275(5):1003-17. 2008-01-25 [PMID: 18221492] (Enzyme Assay, Human) Enzyme Assay Human
Yoon H, Laxmikanthan G, Lee J, Blaber SI, Rodriguez A, Kogot JM, Scarisbrick IA, Blaber M Activation profiles and regulatory cascades of the human kallikrein-related peptidases. J. Biol. Chem., 2007-09-06;282(44):31852-64. 2007-09-06 [PMID: 17823117] (Enzyme Assay) Enzyme Assay

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Gene Symbol KLK4