Recombinant Human PNP Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Product Details

Recombinant Human PNP Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie® Blue stain at 5 μg per lane
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by the phosphorolysis of 7-methyl-6-thioguanosine. The specific activity is >35,000 pmol/min/μg, as measured under the described conditions.
E. coli-derived human Purine Nucleoside Phosphorylase/PNP protein
Met1-Ser289, with a C-terminal 6-His tag
Accession #
N-terminal Sequence
Predicted Molecular Mass
33 kDa
30-35 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 and NaCl.
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, -70 °C as supplied.
  • 3 months, -70 °C under sterile conditions after opening.

Assay Procedure

  • Assay Buffer: 50 mM Potassium Phosphate, pH 7.4
  • Recombinant Human Purine Nucleoside Phosphorylase/PNP (rhPNP) (Catalog # 6486-NP)
  • Substrate: 7-Methyl-6-thioguanosine (MESG) (Berry & Associates, Catalog # PR 3790), 10 mM stock in DMSO
  • 96-well Clear Plate (Costar, Catalog # 92592)
  • Plate Reader (Model: SpectraMax Plus by Molecular Devices) or equivalent
  1. Dilute rhPNP to 0.2 ng/μL in Assay Buffer.
  2. Dilute Substrate to 800 μM in Assay Buffer.
  3. Load 50 μL of 0.2 ng/μL rhPNP into the microplate and start the reaction by adding 50 μL of Substrate. Include a Substrate Blank containing 50 μL of Assay Buffer and 50 μL of Substrate.
  4. Read at an absorbance of 360 nm in kinetic mode for 5 minutes.
  5. Calculate specific activity:

     Specific Activity (pmol/min/µg) =

Adjusted Vmax* (OD/min) x well volume (L) x 1012 pmol/mol
ext. coeff** (M-1cm-1) x path corr.*** (cm) x amount of enzyme (µg)

     *Adjusted for Substrate Blank 
     **Using the extinction coefficient 6220 M-1cm-1 
     ***Using the path correction 0.320 cm
     Note: the output of many spectrophotometers is in mOD Per Well:
  • rhPNP: 0.010 μg
  • Substrate: 400 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: Purine Nucleoside Phosphorylase/PNP

Purine Nucleoside Phosphorylase (PNP) catalyzes the phophorolysis of N-ribosidic bonds of purine nucleosides and deoxynucleosides. Physiological substrates of PNP include inosine, guanosine, and 2'-deoxyguanosine, but not adenosine (1). PNP is expressed in most tissues, with markedly greater expression in lymphoid tissues. Genetic deficiencies of PNP result in severely compromised T‑lymphocyte function and neurologic dysfunction (2, 3). PNP is used in assays for the measurement of inorganic phosphate (4).

  1. Schramm, V.L. (1998) Annu. Rev. Biochem. 67:693.
  2. Stoop, W. et al. (1977) N. Eng. J. Med. 296:651.
  3. Markert, M.L. (1991) Immunodefic. Rev. 3:45.
  4. Webb, M.R. (1992) Proc. Natl. Acad. Sci. USA. 89:4884.
Entrez Gene IDs
4860 (Human)
Alternate Names
EC; FLJ94043; FLJ97288; Inosine phosphorylase; MGC117396; MGC125915; MGC125916; NPFLJ97312; nucleoside phosphorylase; PNP; PRO1837; PUNP; purine nucleoside phosphorylase; purine-nucleoside:orthophosphate ribosyltransferase

Product Specific Notices

Coomassie is a registered trademark of Imperial Chemical Industries Ltd.


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