Recombinant Human Carboxypeptidase B1/CPB1 Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Product Details

Recombinant Human Carboxypeptidase B1/CPB1 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 a colorimetric peptide substrate, Hippuryl-Arg. The specific activity is >1,000 pmol/min/µg, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Carboxypeptidase B1/CPB1 protein
His16-Tyr417, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Structure / Form
Pro form
Predicted Molecular Mass
47 kDa
45 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 MES 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, 150 mM NaCl, 10 mM CaCl2, 0.05% Brij-35, pH 7.5 (TCNB)
  • Assay Buffer: 50 mM Tris, 100 mM NaCl, pH 7.5
  • Recombinant Human Carboxypeptidase B1/CPB1 (rhCPB1) (Catalog # 2897-ZN)
  • Trypsin (Sigma, Catalog # T-1426)
  • Substrate: Hippuryl-R (Sigma, Catalog # H-2508), 25 mM in diH2O
  • 96 well clear UV-transparent microplate (Corning, Catalog # 3635)
  • Plate Reader (Model: SpectraMax Plus by Molecular Devices) or equivalent
  1. Dilute rhCPB1 to 100 μg/mL with 1.0 μg/mL Trypsin in Activation Buffer.
  2. Incubate at room temperature for 30 minutes.
  3. Dilute active rhCPB1 to 2 μg/mL in Assay Buffer.
  4. Dilute Substrate to 2 mM in Assay Buffer.
  5. Load 50 μL of the 2 μg/mL rhCPB1 into a plate. Include a Substrate blank with 50 μL of Assay Buffer.
  6. Start the reaction by adding 50 μL of diluted Substrate into wells.
  7. Read in kinetic mode for 5 minutes at an absorbance of 254 nm.
  8. Calculate specific activity using the following formula:

     Specific Activity (pmol/min/µg) =

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

     *Adjusted for Substrate Blank
     **Derived using calibration standard Hippuric acid (Sigma, Catalog # 112003).

Per Well:
  • rhCPB1: 0.1 μg
  • Substrate: 1 mM
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: Carboxypeptidase B1/CPB1

Carboxypeptidase B1, encoded by the CPB1 gene, specifically cleaves the C-terminal Arg and Lys residues with a preference for Arg (1). Expressed mainly in pancreas, CPB1 is a useful serum marker for acute pancreatitis (2). The deduced amino acid sequence of human CPB1 consists of a signal peptide (residues 1 to 15), a pro region (residue 16 to 110), and a mature chain (residues 111 to 417). The purified rhCPB1 corresponds to the pro form, which can be activated by trypsin, the only pancreatic protease capable of generating active enzyme from the zymogen in vitro (1).

  1. Aviles, F.X. and J. Vendrell (2004) in Handbook of Proteolytic Enzymes (ed. Barrett, A.J. et al.) p. 831, Academic Press, San Diego.
  2. Yamamoto, K.K. et al. (1992) J. Biol. Chem. 267:2575.
Entrez Gene IDs
1360 (Human); 76703 (Mouse)
Alternate Names
carboxypeptidase B; carboxypeptidase B1 (tissue); Carboxypeptidase B1; CPB; CPB1; DKFZp779K1333; EC 3.4.17; EC; Pancreas-specific protein; PASP; PCPB; procarboxypeptidase B


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