Recombinant Human Aminopeptidase P1/XPNPEP1 Protein, CF

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Recombinant Human Aminopeptidase P1/XPNPEP1 Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
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, H-Lys(2-Aminobenzoyl)-Pro-Pro-p-Nitroanilide (K(Abz)PP-pNA). The specific activity is >1,300 pmol/min/µg, as measured under the described conditions.
E. coli-derived human Aminopeptidase P1/XPNPEP1 protein
Met1-His623 & Pro2-His623, both with a C-terminal 6-His tag
Accession #
N-terminal Sequence
Met1 & Pro2
Predicted Molecular Mass
71 kDa
71 kDa, reducing conditions

Product Datasheets

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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, NaCl and Glycerol.
Shipping The product is shipped with dry ice or equivalent. 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

  • Assay Buffer: 50 mM Tris, 250 mM NaCl, 0.5 mM MnCl2, pH 8.0
  • Recombinant Human Aminopeptidase P1/XPNPEP1 (rhXPNPEP1) (Catalog # 2970-ZN)
  • Substrate: Lys(ABZ)Pro-Pro-PNA (Bachem, Catalog # L-1980), 10 mM stock in deionized water
  • F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
  • Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent
  1. Dilute rhXPNPEP1 to 0.5 ng/µL in Assay Buffer.
  2. Dilute Substrate to 100 µM in Assay Buffer.
  3. Load into plate 50 µL of 0.5 ng/µL of rhXPNPEP1 (25 ng/well), and start the reaction by adding 50 µL of 100 µM Substrate. Include a Substrate Blank of 50 μL Assay Buffer and 50 µL of 100 µM Substrate.
  4. Read at excitation and emission wavelengths of 320 nm and 410 nm (top read), respectively, in kinetic mode for 5 minutes.
  5. 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 Abz-Gly (Bachem, Catalog # E-2920).

Per Well:
  • rhXPNPEP1: 0.025 µg
  • Substrate: 50 µM
Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: Aminopeptidase P1/XPNPEP1

The human XPNPEP1 gene encodes aminopeptidase P1 (APP1), which is also known as X-prolyl aminopeptidase with gene aliases of SAMP, XPNPEP, XPNPEPL, and XPNPEPL1 (1‑3). It is a member of the M24 family of metalloproteases, which also contains methionine aminopeptidases, X-Pro dipeptidase, aminopeptidase P2, aminopeptidase P homolog, proliferation-associated protein 1, and suppressor of Ty homolog or chromatin-specific transcription elongation factor large subunit (4). It is a soluble enzyme, in contrast to the GPI-anchored APP2 encoded by XPNPEP2 (5). Human APP1 is widely expressed (3). The purified rhAPP1 is an active aminopeptidase, removing a N‑terminal amino acid from a peptide that contains a Pro residue at the second position. The amino acid sequence of human APP1 is 99%, 97%, 95%, 74% and 73% identical to that of canine, bovine, mouse/rat, Xenopus and zebrafish, respectively.

  1. Cottrell, G.S. et al. (2000) Biochemistry 39:15121.
  2. Sprinkle, T.J. et al. (2000) Arch. Biochem. Biophys. 378:51.
  3. Vanhoof, G. et al. (1997) Cytogenet. Cell Genet. 78:275.
  4. Turner, A.J. and G.S. Cottrell (2004) in Handbook of Proteolytic Enzymes (ed. Barrett, A.J. et al.) pp. 931 - 933, Elsevier Academic Press, San Diego. 
  5. Simmons, W.H. (2004) in Handbook of Proteolytic Enzymes (ed. Barrett, A.J. et al.) pp. 934 - 937, Elsevier Academic Press, San Diego. 
Entrez Gene IDs
7511 (Human)
Alternate Names
Aminoacylproline aminopeptidase; Aminopeptidase P1; APP1; Cytosolic aminopeptidase P; cytosolic; EC; SAMP; xaa-Pro aminopeptidase 1; XPNPEP1; XPNPEPLX-prolyl aminopeptidase (aminopeptidase P)-like; X-prolyl aminopeptidase (aminopeptidase P) 1, soluble; X-prolyl aminopeptidase 1, soluble


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