Recombinant Human Kallikrein 8/Neuropsin Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Recombinant Human Kallikrein 8/Neuropsin Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to cleave the fluorogenic peptide substrate Boc-VPR-AMC (Catalog # ES011). The specific activity is >500 pmol/min/µg, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Kallikrein 8/Neuropsin protein
Gln29-Gly260, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
No results obtained: Gln29 predicted
Structure / Form
Pro form
Predicted Molecular Mass
26 kDa
37-39 kDa, reducing conditions

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Supplied as a 0.2 μm filtered solution in Tris and NaCl.
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: 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 opening.

Assay Procedure

  • Activation Buffer: 50 mM Tris, pH 8.0
  • Assay Buffer: 50 mM Tris, pH 9.0
  • Recombinant Human Kallikrein 8/Neuropsin (rhKLK8) (Catalog # 2025-SE)
  • Lysyl-Endopeptidase (Wako BioProducts, Catalog # 129-02541), 20 U/mL in PBS
  • Substrate: BOC-Val-Pro-Arg-AMC (Catalog # ES011), 10 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 rhKLK8 to 200 µg/mL in Activation Buffer.
  2. Dilute Lysyl-Endopeptidase to 0.4 mU/mL in Activation Buffer.
  3. Activate rhKLK8 by combining equal volumes of diluted rhKLK8 and Lysyl-Endopeptidase.
  4. Incubate at 37 °C for 30 minutes.
  5. Dilute activated rhKLK8 to 1 ng/µL in Assay Buffer.
  6. Dilute Substrate to 200 µM in Assay Buffer.
  7. Load 50 µL of 1 ng/µL rhKLK8 into the plate, and start the reaction by adding 50 µL of 200 µM Substrate. Include a Substrate Blank containing 50 µL of Assay Buffer and 50 µL of 200 µM Substrate.
  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 (AMC) (Sigma, Catalog # A-9891).

Per Well:
  • rhKLK8: 0.050 µg
  • Substrate: 100 µM
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Background: Kallikrein 8/Neuropsin

Kallikrein 8 (KLK8), also known as neuropsin or ovasin, is a member of the human tissue kallikrein family (1). Two alternatively spliced forms exist, resulting in 260 (isoform 1) and 305 (isoform 2) amino acid sequences, respectively (2). Isoform 1 consists of a signal peptide (residues 1 to 28), a short pro peptide (residues 29 to 32) and the mature chain (residues 33 to 260). Isoform 2 is identical to isoform 1, except that a 45 amino acid segment is inserted in isoform 2 between residues 23 and 24 in isoform 1. Isoform 1 is predominantly expressed in pancreas whereas isoform 2 is preferentially expressed in adult brain and hippocampus, although both forms are expressed in fetal brain and placenta in comparable levels. The brain function of KLK8 seems evident in neuropsin knockout mice that showed abnormalities of synapses and neurons and predisposation to global seizure activity (3, 4). KLK8 is a novel marker for ovarian and cervical cancer carcinomas (5, 6). Recombinant human KLK8, after being activated by lysyl endopeptidase, can cleave fibronectin and several small peptide substrates (7, 8). This activity can be inhibited by recombinant human Serpin A5, recombinant human Serpin F2 and AEBSF (Catalog # 1266-PI, 1470-PI and EI001, respectively). Recombinant human KLK8 produced by R&D Systems corresponds to isoform 1.

  1. Yousef, G.M. and E.P. Diamandis (2001) Endocrine Rev. 22:184.
  2. Mitsui, S. et al. (1999) Eur. J. Biochem. 260:627.
  3. Hirata, A. et al. (2001) Mol. Cell. Neurosci. 17:600.
  4. Davies, B. et al. (2001) J. Neurosci. 21:6993.
  5. Kishi, T. et al. (2003) Cancer Res. 63:2771.
  6. Cane, S. et al. (2004) Am. J. Obstet. Gynecol. 190:60.
  7. Oka, T. et al. (2002) J. Biol. Chem. 277:14724.
  8. Shimizu, C. et al. (1998) J. Biol. Chem. 273:11189.
Entrez Gene IDs
11202 (Human)
Alternate Names
EC 3.4.21; EC; hK8; HNP; kallikrein 8 (neuropsin/ovasin); Kallikrein 8; kallikrein-related peptidase 8; KLK8 protein type 1; KLK8 protein type 2; KLK8; neuropsin type 1; neuropsin type 2; Neuropsin; NP; NRPN; Ovasin; PRSS19; PRSS19kallikrein-8; Serine protease 19; Serine protease TADG-14; TADG14neuropsin; Tumor-associated differentially expressed gene 14 protein

Citations for Recombinant Human Kallikrein 8/Neuropsin Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

5 Citations: Showing 1 - 5
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  1. Neuropsin cleaves EphB2 in the amygdala to control anxiety.
    Authors: Attwood BK, Bourgognon JM, Patel S, Mucha M, Schiavon E, Skrzypiec AE, Young KW, Shiosaka S, Korostynski M, Piechota M, Przewlocki R, Pawlak R
    Nature, 2011;473(7347):372-5.
    Species: Human
    Sample Types: Whole Cells
    Applications: Enzyme Assay
  2. Isolation of SPINK6 in human skin: selective inhibitor of kallikrein-related peptidases.
    Authors: Meyer-Hoffert U, Wu Z, Kantyka T, Fischer J, Latendorf T, Hansmann B, Bartels J, He Y, Glaser R, Schroder JM
    J. Biol. Chem., 2010;285(42):32174-81.
    Species: Human
    Sample Types: Peptide
    Applications: Enzyme Assay
  3. Specific inhibition of tissue kallikrein 1 with a human monoclonal antibody reveals a potential role in airway diseases.
    Authors: Sexton DJ, Chen T, Martik D, Kuzmic P, Kuang G, Chen J, Nixon AE, Zuraw BL, Forteza RM, Abraham WM, Wood CR
    Biochem. J., 2009;422(2):383-92.
    Species: Human
    Sample Types: Antibody
    Applications: Surface Plasmon Resonance
  4. Activation profiles and regulatory cascades of the human kallikrein-related peptidases.
    Authors: Yoon H, Laxmikanthan G, Lee J, Blaber SI, Rodriguez A, Kogot JM, Scarisbrick IA, Blaber M
    J. Biol. Chem., 2007;282(44):31852-64.
    Species: N/A
    Sample Types: Peptide
    Applications: Enzyme Assay
  5. Inhibition of kallikrein-related peptidases by the serine protease inhibitor of Kazal-type 6.
    Authors: Kantyka T, Fischer J, Wu Z, Declercq W, Reiss K, Schroder J, Meyer-Hoffert U
    Peptides, 0;32(6):1187-92.
    Applications: Bioassay


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