Corn Trypsin Inhibitor

Description

Corn trypsin inhibitor (CTI) is a small protein that is localized in the kernels of most species of corn. CTI is not only an inhibitor of trypsin, but is also a specific inhibitor of human factor XIIa when tested in blood clotting experiments (1-6). The inhibitor forms a one-to-one complex with either trypsin or factor XIIa, and when added to plasma, prolongs the activated partial thromboplastin time without affecting the PT assay (6). The specificity for factor XIIa makes the inhibitor useful for the segregation and study of coagulation reactions (6). The protein is comprised of 112 amino acids which yields a calculated molecular weight of 12,028 (7). The calculated molecular weight and that which has been determined by sedimentation equilibrium analyses of the purified protein (12,500) are in good agreement (3). A comparison of the amino acid sequence of CTI to that of other trypsin or serine protease inhibitors reveals little or no similarities (7). CTI is purified using a combination of published procedures (3,4). To begin the purification process, CTI is extracted from the kernels of fresh sweet corn into a physiologic buffer. The extract is then de-fatted using acetone, and the protein is further purified by employing gel filtration and ion-exchange chromatography. The final CTI preparation appears as a single band by SDS-PAGE analyses under both reducing and non-reducing conditions. Preparations of CTI are tested for the ability to prolong the aPTT assay without affecting the PT assay. The specific activity of each lot of CTI is determined, and one unit is defined as the amount of CTI required to double the aPTT of normal human plasma. Purified CTI is formulated in 20 mM Tris, 0.3 M NaCl, pH 7.4 and should be stored frozen at -20°C or colder.

• SUPPLIER:

  Haematologic TechnologiesProlytix

• STATUS:

  In Stock

• SIZE:

  1 mg