Aprotinin from bovine lung (C15-1292-207)

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.

Application

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.

Biochem/physiol Actions

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.

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.

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.