Aprotinin from bovine lung

lyophilized powder, 3-8 TIU/mg solid

Bovine pancreatic trypsin inhibitor, BPTI, Trypsin inhibitor (basic), Trasylol
Empirical Formula (Hill Notation):
CAS Number:
Molecular Weight:
EC Number:
MDL number:

Quality Level

biological source

bovine lung


lyophilized powder

specific activity

3-8 TIU/mg solid

mol wt



H2O: ≥5 mg/mL

storage temp.


InChI key


Gene Information

cow ... PTI(404172)

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General description

Aprotinin from bovine lung is a globular polypeptide monomer with a molecular weight of 6.5 kDa. Commonly used as a non-specific serine protease inhibitor, aprotinin contains an antiparallel β sheet, N-terminal 310 helix and C-terminal and α helix. Aprotinin residues from amino acids 13 - 18 are essential for binding to serine proteases.


Aprotinin from bovine lung has been used:
  • as a protease inhibitor in radioimmunoprecipitation assay buffer (RIPA) for the homogenization of cardiac microvascular endothelial cells (CMECs)(4) and mammary epithelial cells
  • in angiogenesis assay for fibroblast
  • in the proteomic stabilization of saliva supernatant

Aprotinin is largely used as an inhibitor of trypsin.


10, 25, 100, 250 mg in poly bottle
1, 5 mg in glass bottle

Biochem/physiol Actions

Aprotinin is a competitive serine protease inhibitor that forms stable complexes with and blocks the active sites of enzyme. This binding is reversible, and most aprotinin-protease complexes will dissociate at extreme pH levels >10 or <3. Structurally, Aprotinin is a monomeric globular protein derived from bovine lung that consists of 58 amino acids, arranged in a single polypeptide chain with three crosslinking disulfide bridges.
Aprotinin inhibits proteases like trypsin, plasmin, chymotrypsin and thrombin. It blocks the bradykinin synthesis from kininogen. It is useful for treating blood loss during surgery.

Unit Definition

One Trypsin Inhibitor Unit (TIU) will decrease the activity of two trypsin units by 50%, where one trypsin unit will hydrolyze 1.0 μmole of N-alpha-benzoyl-DL-arginine p-nitroanilide per minute at pH 7.8 and 25°C. Another commonly used unit is the KIU, with 1 TIU = 1,300 KIU.

Preparation Note

This product is a lyophilized powder with activity of 3-8 TIU/mg of solid powder. Aprotinin is freely soluble in water (>10 mg/mL) and in aqueous buffers of low ionic strengths. Dilute solutions tend to be less stable than concentrated ones, though solution stability also depends on pH. Aprotinin is relatively stable against denaturation - only thermolysin has been found capable of degrading it at 60-80°C. Sterilizaiton of Aprotinin can be achieved through filtration by a 0.2 μm filter.

Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves


NONH for all modes of transport

WGK Germany


Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

  1. When using Product A1153, Aprotinin from bovine lung, what is the conversion from KIU to TIU? 

    According to data from our labs here at Sigma, there are approximately 1300 KIU per 1 TIU.  This, along with other useful information, can be found on the product information sheet available at our website:  A1153 Product Information Sheet  

  2. Is Aprotinin from bovine lung, Product A1153, the same as Trasylol?

    Trasylol is the Bayer AG registered trademark name for this material.

  3. How should I store solutions of Aprotinin from bovine lung, Product A1153?

    Sterile solutions of aprotinin may be stored at 4 °C or as frozen aliquots at -20 °C.

  4. What are typical concentrations of Aprotinin from bovine lung, Product A1153, to use as a protease inhibitor?

    Typical concentration of Aprotinin to be used as a protease inhibitor is 1 μM or approximately 6.5 μg/ml.

  5. What type of inhibitor is Aprotinin from bovine lung, Product A1153?

    Aprotinin is a competitive serine protease inhibitor which forms stable complexes that block the active site of the enzyme. 

  6. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  7. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  8. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  9. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  10. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

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While aprotinin and bovine pancreatic trypsin inhibitor (BPTI) are the same protein sequence, the term aprotinin is typically used when describing the protein derived from bovine lung.
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