Human alpha 2-Macroglobulin Protein, CF

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Product Details
Citations (5)
Supplemental Products

Human alpha 2-Macroglobulin Protein, CF Summary

Product Specifications

>90%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to trap trypsin. The trapped trypsin is no longer able to interact with protein substrates or inhibitors, but still able to cleave small peptide substrates or inhibitors. Human alpha 2-Macroglobulin has an IC50 value of <5 nM, as measured under the described conditions.
Human plasma-derived alpha 2-Macroglobulin protein
The human plasma used for the isolation of this product was certified by the supplier to be HIV-1 and HBsAg negative at the time of shipment. Human blood products should always be treated in accordance with universal handling precautions.
N-terminal Sequence
Structure / Form
Disulfide-linked homo-oligomer
90-170 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 NaH2PO4, NaCl and Glycerol.
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

  • Assay Buffer: 50 mM Tris, 10 mM CaCl2, 150 mM NaCl, 0.05% (w/v) Brij-35, pH 7.5 (TCNB)
  • Human alpha 2-Macroglobulin (h alpha 2-Macroglobulin) (Catalog # 1938-PI)
  • Recombinant Human Serpin F2 (rhSerpin F2) (Catalog # 1470-PI)
  • Recombinant Human Active Trypsin 3/PRSS3 (rhTrypsin 3) (Catalog # 3714-SE)
  • Substrate: MCA-Arg-Pro-Lys-Pro-Val-Glu-NVAL-Trp-Arg-Lys(DNP)-NH2 (Catalog # ES002)
  • F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
  • Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent
  1. Dilute rhTrypsin 3 to 1.28 µg/mL with Assay Buffer.
  2. Prepare a curve of h alpha 2-Macroglobulin with Assay Buffer. Dilute h alpha 2-Macroglobulin (MW: 720000 Da) to the following concentrations: 200 nM, 100 nM, 50 nM, 25 nM, 12.5 nM, 6.25 nM, 3.125 nM, and 0.3125 nM.
  3. Combine 30 µL of h alpha 2-Macroglobulin curve with 30 µL of 1.28 µg/mL rhTrypsin 3. Include a control containing 30 µL of Assay Buffer with 30 µL of rhTrypsin 3 in duplicate. Also include a h alpha 2-Macroglobulin control in duplicate for each sample tested containing 30 µL of 200 nM h alpha 2-Macroglobulin and 30 µL Assay Buffer.
  4. Incubate at 37 °C for 1 hour.
  5. Dilute rhSerpin F2 to 40 µg/mL with Assay Buffer.
  6. Add 60 µL of 40 µg/mL rhSerpin F2 to each reaction.
  7. Incubate at 37 °C for 15 minutes.
  8. Dilute Substrate to 20 µM in Assay Buffer.
  9. Load into plate 50 µL of h alpha 2-Macroglobulin curve containing rhTrypsin 3 and rhSerpin F2, and start the reaction by adding 50 µL of 20 µM Substrate to each well.
  10. Read at excitation and emission wavelengths of 320 nm and 405 nm (top read), respectively, in kinetic mode for 5 minutes.
  11. Derive the 50% inhibiting concentration (IC50) of h alpha 2-Macroglobulin, by its trapping of rhTrypsin 3, toward rhSerpin F2 activity by plotting RFU/min (or specific activity) vs. concentration (h alpha 2-Macroglobulin) with 4-PL fitting.
  12. The specific activity for rhTrypsin 3 at each point may be determined 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 h alpha 2-Macroglobulin control

     **Derived using calibration MCA-Pro-Leu-OH (Bachem, Catalog # M-1975).

Per Well:
  • h alpha 2-Macroglobulin: 25, 12.5, 6.25, 3.125, 1.563, 0.781, 0.391, and 0.0391 nM
  • rhTrypsin 3: 0.016 µg
  • rhSerpin F2: 1 µg
  • Substrate: 10 µM
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Background: alpha 2-Macroglobulin

Human alpha 2-macroglobulin (h alpha 2M) is a serum glycoprotein that has sequence similarity to other members of the alpha 2M family including complement components C3, C4 and C5 (1). alpha 2M is synthesized as a polypeptide of 1474 amino acids with a signal peptide (23 residues) (2). The mature protein is a tetramer (720 kDa) of 4 identical subunits (180 kDa), which form two disulfide bond-linked dimers. As a general and irreversible protease inhibitor implicated in many processes, alpha 2M is able to inhibit all four classes of proteases by a unique trapping mechanism. The bait region of h alpha 2M (residues 690‑728) contains specific cleavage sites for different proteases. The cleavage of the bait region by a protease induces a conformation change in alpha 2M, which then traps and forms a covalent bond with the protease. The trapped protease remains active against small peptide substrates but loses its ability to interact with large protein substrates or inhibitors.

  1. Sottrup-Jensen, L. et al. (1985) Proc. Natl. Acad. Sci. USA 82:9.
  2. Kan, C.C. et al. (1985) Proc. Natl. Acad. Sci. USA 82:2282.
Entrez Gene IDs
2 (Human)
Alternate Names
A2M; alpha 2Macroglobulin; alpha 2-Macroglobulin; alpha-2-M; alpha-2-macroglobulin; C3 and PZP-like alpha-2-macroglobulin domain-containing protein 5; CPAMD5; CPAMD5DKFZp779B086; FWP007; S863-7

Citations for Human alpha 2-Macroglobulin Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

5 Citations: Showing 1 - 5
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  1. Post-Translational Regulation And Proteolytic Activity Of The Metalloproteinase Adamts8
    Authors: S Santamaria, DR Martin, X Dong, K Yamamoto, SS Apte, J Ahnström
    The Journal of Biological Chemistry, 2021;0(0):101323.
    Species: Human
    Sample Types:
    Applications: Bioassay
  2. Exosomes from acellular Wharton's jelly of the human umbilical cord promotes skin wound healing
    Authors: N Bakhtyar, MG Jeschke, E Herer, M Sheikholes, S Amini-Nik
    Stem Cell Res Ther, 2018;9(1):193.
    Species: Mouse
    Sample Types: Whole Cells
    Applications: Bioassay
  3. Effects of sFlt-1 and alpha 2-macroglobulin on vascular endothelial growth factor-induced endothelin-1 upregulation in human microvascular endothelial cells.
    Authors: Yi K, Jung S, Cho G, Seol H, Hong S, Oh M, Kim H
    Placenta, 2014;35(1):64-9.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay
  4. Regulated proteolytic processing of Reelin through interplay of tissue plasminogen activator (tPA), ADAMTS-4, ADAMTS-5, and their modulators.
    Authors: Krstic D, Rodriguez M, Knuesel I
    PLoS ONE, 2012;7(10):e47793.
    Species: Human
    Sample Types: Recombinant Protein
    Applications: Enzyme Assay
  5. Enzymatic properties of human kallikrein-related peptidase 12 (KLK12).
    Authors: Memari&lt;/LastName&gt;&lt;ForeNam N&lt;/Initial, Memari N, Jiang W, Diamandis EP, Luo LY
    Biol. Chem., 2007;388(4):427-35.
    Species: Human
    Sample Types: Recombinant Protein
    Applications: Enzyme Assay


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