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United States Biological

aprotininAprotinin inhibits the activity of several proteolytic enzymes such as chymotrypsin, kallikrein, plasmin and trypsin. It is present in blood and in most tissues, with a high concentration in lung, and inhibits pro-inflammatory cytokine release and maintains glycoprotein homeostasis. It is one of the many protease inhibitors offered by United States Biological, including our protease cocktail which is used to generally inhibit proteases (serine, cysteine, aspartic and metalloproteases).

Pancreatic TrypsinPancreatic Trypsin

USBio's anti-Apoprotinin Antibodies:

Aprotinin (Pancreatic trypsin inhibitor) Mab Mo xBo
A2300-01 recognizes bovine aprotinin immobilized on a solid phase or free in solution. Epitope is different from A2300-01A, A2300-01B (biotinylated form of A2300-01A) and A2300-01C.

Aprotinin (Pancreatic trypsin inhibitor) Mab Mo xBo
A2300-01A when biotinylated (or A2300-01B), forms an antibody pair with A2300-01C (as capture antibody) for high-sensitivity sandwich ELISA of aprotinin at sample concentrations of 0.6-20ug/ml.

Aprotinin (Biotin) (Pancreatic trypsin inhibitor) Mab Mo xBo
Biotinylated A2300-01A

Aprotinin (Pancreatic trypsin inhibitor) Mab Mo xBo
A2300-01C forms an antibody pair with A2300-01B (as biotinylated detection antibody) for sandwich ELISA of aprotinin at sample concentrations of 0.6-20ug/ml.

Newsletter Special:
Aprotinin (Pancreatic trypsin inhibitor), A2300-04

This month's Special:
Biologically Relevant
Noggin, N3100-05E

Expression of pluripotent stem cell markers of hES colonies cultured in the presence of Noggin (N3100-05E,10-20pg/ml) expressed in human cells. A. Green TRA1-60 B. Green SSEA-4 C. Green TRA1-81 D. OCT 3/4 (Blue=Nuclear)

Noggin is a secreted homodimeric glycoprotein that is an antagonist of bone morphogenetic proteins (BMPs). During culture of human embryonic stem (hES) cells without feeder layer or conditioned medium (but with addition of FGF basic), the addition of Noggin allows the stem cells to maintain their undifferentiated, pluripotent state. Commercially available Noggin products are produced in a variety of forms none of which are authentic: non-glycosylated protein expressed in E. coli; glycosylated Fc-fusion protein expresed in NS0, for example. USBiological supplies Noggin in a stable, engineered human 293 cell expression system. The protein is expressed as an authentic glycosylated, disulfide-linked dimer.

promo code 090109

Bovine Pancreatic Trypsin Inhibitor

Aprotinin, also called bovine pancreatic trypsin inhibitor (BPTI), is a serine proteinase inhibitor found in bovine pancreas, parotid gland and lung. Aprotinin inhibits several serine proteases, specifically trypsin, chymotrypsin, plasmin and kallikrein, leading to the inhibition of the formation of factor XIIa and as a result, both the intrinsic pathway of coagulation and fibrinolysis are inhibited. Aprotinin has been used therapeutically as an antifibrinolytic agent under the name Trasylol (Bayer) to reduce blood loss during cardiopulmonary bypass surgery but this use has been associated with an increased frequency of acute renal injury.
Aprotinin is a monomeric (single-chain) globular polypeptide derived from bovine lung tissue; it has a Molecular Weight of 6512 and consists of 16 different amino acids arranged in a chain of 58 amino acid residues. Its amino acid sequence is RPDFC LEPPY TGPCK ARIIR YFYNA KAGLC QTFVY GGCRA KRNNF KSAED CMRTC GGA (1).
The stability of the molecule is due to the 3 disulfide bonds linking the 6 cysteine members of the chain (Cys5-Cys55, Cys14-Cys38 and Cys30-Cys51) (2).  The lysine (15)-alanine (16) sequence on this strongly basic polypeptide represents the active center.

Aprotinin is Kunitz-type serine protease inhibitor. It is one of the most thoroughly studied proteins in terms of structure and folding pathway. BPTI was one of the first proteins to have its structure solved by NMR spectroscopy (4,5).

For a time Aprotinin (Trasylol, Bayer) was used as a medication administered by injection to reduce bleeding during complex surgery, such as heart and liver surgery. Its main effect is the slowing down of fibrinolysis, the process that leads to the breakdown of blood clots. The aim in its use is to decrease the need for blood transfusions during surgery, as well as end-organ damage due to hypotension (low blood pressure) as a result of marked blood loss. The drug was temporarily withdrawn worldwide in 2007 after studies suggested that its use increased the risk of complications or death (5);  this was confirmed by follow-up studies. Trasylol was entirely and permanently withdrawn in May 2008 (except for very restricted research use).

In cell biology aprotinin is widely used as an enzyme inhibitor to prevent protein degradation during lysis or homogenization of cells and tissues.  It is found in many protease inhibitor cocktails, such as US Biological’s own P9070, Protease Inhibitor Cocktail. This basic polypeptide inhibits numerous serine proteases by binding to the active site of the enzyme, forming tight  complexes. It inhibits above all plasmin, kallikrein,trypsin, chymotrypsin and urokinase, but not carboxypeptidase A and B, papain, pepsin, subtilisin, thrombin and factor X. It is used in cell culture to prevent proteolytic damage to cells and to extend the lifetime of cells.



1. Kassell B, Radicevic M, Ansfield MJ, Laskowski M (1965). "The basic trypsin inhibitor of bovine pancreas. IV. The linear sequence of the 58 amino acids". Biochem. Biophys. Res. Commun. 18: 255–258.

2. Berndt, K.D., Güntert, P., Orbons, L.P.M. and Wüthrich, K. (1992) J. Mol. Biol. 227; 757-775.  Determination of a high-quality nuclear magnetic resonance solution structure of the bovine pancreatic trypsin inhibitor and comparison with three crystal structures.

3. Wagner G, Wüthrich K. Sequential resonance assignments in protein 1H nuclear magnetic resonance spectra. Basic pancreatic trypsin inhibitor. J.Mol. Biol. (1982) 155:347–366.

4. Kassell B, Laskowski M (1965). "The basic trypsin inhibitor of bovine pancreas. V. The disulfide linkages". Biochem. Biophys. Res. Commun. 20 (4): 463–468.
5. Mangano DT, Tudor IC, Dietzel C (2006). "The risk associated with aprotinin in cardiac surgery". N. Engl. J. Med. 354: 353–65.