Recombinant Human Serpin C1/Antithrombin-III Protein, CF


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Product Details

Reactivity HuSpecies Glossary
Applications Inhibition Activity

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Recombinant Human Serpin C1/Antithrombin-III Protein, CF Summary

Details of Functionality
Measured by its ability to inhibit Recombinant Human Coagulation Factor II/Thrombin (Catalog # 1473-SE) cleavage of a fluorogenic peptide substrate Boc-VPR-AMC (Catalog # ES011). The IC50 value is <5 nM, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Serpin C1/Antithrombin-III protein
His33-Lys464, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Protein/Peptide Type
Recombinant Enzymes
>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Note
<1.0 EU per 1 μg of the protein by the LAL method.


  • Inhibition Activity
Theoretical MW
50 kDa.
Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
55-65 kDa, reducing conditions
Read Publications using
1267-PI in the following applications:

Packaging, Storage & Formulations

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 reconstitution.
Lyophilized from a 0.2 μm filtered solution in MES and NaCl.
>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Reconstitution Instructions
Reconstitute at 100 μg/mL in sterile 25 mM MES, 150 mM NaCl, pH 6.5.
Assay Procedure
  • Assay Buffer: 50 mM Tris, 10 mM CaCl2, 150 mM NaCl, 0.05% (w/v) Brij-35, pH 7.5 (TCNB)
  • Recombinant Human Serpin C1/Antithrombin-III (rhSerpin C1) (Catalog # 1267-PI)
  • Recombinant Human Coagulation Factor II/Thrombin (Catalog # 1473-SE)
  • Heparin (Sigma, Catalog # H3393), 20 mg/mL stock in deionized water
  • 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 Thrombin to 1 µg/mL with Heparin at 48.6 µg/mL in Assay Buffer.
  2. Prepare a curve of rhSerpin C1 (MW: 50,378 Da) in Assay Buffer. Make the following serial dilutions: 1000, 500, 250, 125, 62.5, 41.7, 27.8, 13.9, 6.94, and 2.31 nM.
  3. Mix equal volumes of rhSerpin C1 curve dilutions and Thrombin/Heparin mixture. Include a control (in duplicate) containing equal volumes of Assay Buffer and Thrombin/Heparin mixture.
  4. Incubate reaction mixtures at room temperature for 30 minutes.
  5. After incubation, dilute reaction mixtures by 1/5 in Assay Buffer.
  6. Dilute Substrate to 200 µM in Assay Buffer.
  7. In a plate load 50 µL of the diluted reaction mixtures to wells, and start the reaction by adding 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. Derive the 50% inhibition concentration (IC50) for rhSerpin C1 by plotting RFU/min (or specific activity) vs. concentration with 4-PL fitting.
  10. Calculate specific activity for Thrombin at each point using the following formula (if needed):

     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 (Sigma, Catalog # A-9891)

Per Well:
  • Thrombin: 0.005 µg (1.0 nM)
  • rhSerpin C1:  50, 25, 12.5, 6.25, 3.13, 2.09, 1.39, 0.695, 0.347, and 0.116 nM
  • Substrate: 100 µM


This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant Human Serpin C1/Antithrombin-III Protein, CF

  • Antithrombin-III
  • AT3antithrombin-III
  • ATIIIantithrombin III
  • MGC22579
  • serine (or cysteine) proteinase inhibitor, clade C (antithrombin), member 1
  • serine-cysteine proteinase inhibitor clade C member 1
  • Serpin C1
  • serpin peptidase inhibitor, clade C (antithrombin), member 1


Serpin C1 is a member of the Serpin superfamily of the serine protease inhibitors (1). It is the principal plasma Serpin of blood clotting proteases and inhibits thrombin as well as several factors such as Xa (2). Similar to Serpins A5 and D1, its thrombin inhibitory activity is enhanced by heparin. Hereditary and acquired Serpin C1 deficiency is the cause of an increased thrombotic tendency in many cases (3). For example, acquired Serpin C1 deficiency is a common condition in sepsis, after major trauma or surgery (4).

  1. Silverman, G.A. et al. (2001) J. Biol. Chem. 276:33293.
  2. Chuang, Y.-J. et al. (2001) Biochemistry 40:6670.
  3. Vinazzer, H. (1999) Semin. Thromb. Hemost. 25:257.
  4. Risberg, B. (1998) Blood Coagul. Fibrinolysis Suppl. 3:S3.

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Publications for Serpin C1/Antithrombin-III (1267-PI)(6)

We have publications tested in 2 confirmed species: Human, Bacteria.

We have publications tested in 4 applications: Bioassay, ELISA Standard, Enzyme Assay, Enzyme Assay Substrate.

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ELISA Standard
Enzyme Assay
Enzyme Assay Substrate
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Showing Publications 1 - 6 of 6.
Publications using 1267-PI Applications Species
XC Lim, C Huang, SMJM Yatim, SY Chong, SH Tan, X Yang, CL Heldt, J Pedersen, M Talanker, H Modh, MG Wacker, G Pastorin, SP Chan, AM Richards, CJ Charles, MY Chan, JW Wang Temporal Changes in Extracellular Vesicle Hemostatic Protein Composition Predict Favourable Left Ventricular Remodeling after Acute Myocardial Infarction International Journal of Molecular Sciences, 2022-12-25;24(1):. 2022-12-25 [PMID: 36613770] (ELISA Standard, Human) ELISA Standard Human
S Biswas, E Chen, Y Gao, S Lee, I Hewlett, K Devadas Modulation of HIV Replication in Monocyte-Derived Macrophages (MDM) by Host Antiviral Factors Secretory Leukocyte Protease Inhibitor and Serpin Family C Member 1 Induced by Steroid Hormones Viruses, 2022-01-06;14(1):. 2022-01-06 [PMID: 35062299] (Bioassay, Human) Bioassay Human
JW Wang, YN Zhang, SK Sze, SM van de Weg, F Vernooij, AH Schoneveld, SH Tan, HH Versteeg, L Timmers, CSP Lam, DPV de Kleijn Lowering Low-Density Lipoprotein Particles in Plasma Using Dextran Sulphate Co-Precipitates Procoagulant Extracellular Vesicles Int J Mol Sci, 2017-12-29;19(1):. 2017-12-29 [PMID: 29286309] (Bioassay) Bioassay
Ayala-Lujan , Jorge Lu, Vijayakumar , Vidhya, Gong , Mei, Smith , Rachel, Santiago , Araceli, Ruiz-Perez , Fernando Broad spectrum activity of a lectin-like bacterial serine protease family on human leukocytes. PLoS ONE, 2014-09-24;9(9):e107920. 2014-09-24 [PMID: 25251283] (Enzyme Assay, Enzyme Assay Substrate, Bacteria, Human) Enzyme Assay, Enzyme Assay Substrate Bacteria, Human
Memari</LastName><ForeNam N</Initial, Memari N, Jiang W, Diamandis EP, Luo LY Enzymatic properties of human kallikrein-related peptidase 12 (KLK12). Biol. Chem., 2007-04-01;388(4):427-35. 2007-04-01 [PMID: 17391064] (Enzyme Assay, Human) Enzyme Assay Human
Cortesio CL, Jiang W Mannan-binding lectin-associated serine protease 3 cleaves synthetic peptides and insulin-like growth factor-binding protein 5. Arch. Biochem. Biophys., 2006-03-03;449(1):164-70. 2006-03-03 [PMID: 16554018] (Enzyme Assay) Enzyme Assay

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Gene Symbol SERPINC1