Aprotinin bovine recombinant, expressed in Nicotiana, =5 TIU/mg protein, =98% (SDS-PAGE)

EC Number: 232-994-9

MDL Number: MFCD00130541

Preparation Note
Aprotinin is freely soluble in water (>10 mg/ml) and in aqueous buffers of low ionic strengths. Dilute solutions are generally less stable than concentrated ones. Solution stability is pH dependent; a range of 1-12 can be tolerated. Repeated freeze-thaw cycles should be avoided. Due to its compact tertiary structure, aprotinin is relatively stable against denatura­tion due to high temperature, pH extremes, organic solvents, or proteolytic degradation (only thermolysin has been found capable of degrading aprotinin after heating to 60-80 °C). The high basicity of aprotinin causes it to adhere to commonly used dialysis tubing and even gel filtration matrices, but the use of acetylated materials and concentrated salt solutions (=0.1 M NaCl in buffer) minimizes the problem. Sterilization may be achieved by filtration through a 0.2 μm filter.

Contains no animal-derived components or impurities, and is manufactured by transient expression of the aprotinin message in RNA (+)-strand tobacco mosaic virus vectors propagated in non-transgenic Nicotiana plants. This is a recombinant form of the native, bovine-sequence aprotinin, which is traditionally isolated from bovine lung by methods involving fractional precipitation, gel filtration, and ion exchange chromatography. Unlike animal-derived aprotinin, this product is isolated and purified from plant tissue by proprietary methods.

Unit Definition
One trypsin inhibitor unit (TIU) will decrease the activity of 2 trypsin units by 50% where one trypsin unit will hydrolyze 1.0 μmole of N-α-benzoyl-DL-arginine p-nitroanilide (BAPNA) per min at pH 7.8 at 25 °C.

Biochem/physiol Actions
Aprotinin is a competitive serine protease inhibitor that inhibits trypsin, chymotrypsin, kallikrein and plasmin. It had earned a place as an antiinflammatory and antithrombotic adjunct to cardiac surgery, but its value has been called into question. Aprotinin forms stable complexes with and blocks the active sites of enzymes. Binding is reversible with most aprotinin-protease complexes dissociating at pH >10 or <3. Effective concentration equimolar with protease.