详细说明
Purity
>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.
Activity
Measured by its ability to cleave the colorimetric peptide substrate Ac-Phe-Thiaphe-OH in the presence of 5,5’Dithio-bis (2-nitrobenzoic acid) (DTNB). Edwards, K.M. et al. (1999) J. Biol. Chem. 274:30468. The specific activity is >3,000 pmol/min/µg, as measured under the described conditions. See Activity Assay Protocol on www.RnDSystems.com
Source
Mouse myeloma cell line, NS0-derived Lys17-Tyr419, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
AnalysisLys17
Structure / Form
Pro form
Predicted Molecular Mass
47 kDa
SDS-PAGE
42 kDa, reducing conditions
2856-ZN |
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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.
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Assay Procedure
Materials
Assay Buffer: 50 mM Tris, 0.15 M NaCl, 10 mM CaCl2, 0.05% Brij-35, pH 7.5 (TCNB)
Recombinant Human Carboxypeptidase A1/CPA1 (rhCPA1) (Catalog # 2856-ZN)
Trypsin (Sigma, Catalog # T-1426)
Substrate: Ac-Phe-Thiaphe-OH (Peptides International, Catalog # STP-3621-PI),10 mM stock in DMSO
5,5’-dithio-bis(2-nitrobenzoic acid) (DTNB), (Sigma, Catalog # D-8130) 10 mM stock in DMSO
96 well clear plate (Catalog # )
Plate Reader (Model: SpectraMax Plus by Molecular Devices) or equivalent
Dilute rhCPA1 to 100 µg/mL with 1.0 µg/mL Trypsin in Assay Buffer.
Incubate at room temperature for 60 minutes.
Dilute active rhCPA1 to 0.2 µg/mL in Assay Buffer.Combine equal volumes of 10 mM Substrate and 10 mM DTNB. Then, dilute this mixture to 200 µM Substrate, 200 µM DTNB with Assay Buffer.
Load 50 µL of the 0.2 µg/mL rhCPA1 into a clear microplate. Include a substrate blank with 50 µL of Assay Buffer in place of rhCPA1.
Start the reaction by adding 50 µL of 200 µM Substrate into wells.
Read in kinetic mode for 5 minutes at an absorbance of 405 nm.
Calculate specific activity using the following formula:
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 13260 M -1cm -1
***Using the path correction 0.32 cm
Note: the output of many spectrophotometers is in mOD Per Well:
rhCPA1: 0.010 µg
Substrate: 100 µM
DTNB: 100 µM
Background: Carboxypeptidase A1/CPA1
Carboxypeptidase A1 encoded by the CPA1 gene cleaves the C-terminal amide or ester bond of peptides that have a free C-terminal carboxyl group (1). It prefers the C-terminal residues with aromatic or branched aliphatic side chains including Phe, Tyr, Trp, Leu or Ile. It is important in the degradation of food proteins to produce essential amino acids such as Phe and Trp. The deduced amino acid sequence of human CPA1 consists of a signal peptide (residues 1 to 16), a pro region (residue 17 to 110), and a mature chain (residues 111 to 419). The purified recombinant human CPA1 corresponds to the pro form, which can be activated as described in Activity Assay Protocol.
References:
Auld, D.S. (2004) in Handbook of Proteolytic Enzymes (ed. Barrett, et al.) pp. 812, Academic Press, San Diego.
Entrez Gene IDs:
1357 (Human); 109697 (Mouse)
Alternate Names:
carboxypeptidase A1 (pancreatic); Carboxypeptidase A1; CPA; CPA1; EC 3.4.17; EC 3.4.17.1