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, it is also a specific inhibitor of human Factor XIIa when tested in blood clotting experiments. The inhibitor forms a one-to-one complex with either trypsin or Factor XIIa. When added to plasma, it prolongs the activated partial thromboplastin time without affecting the PT assay. The specificity for Factor XIIa makes the inhibitor useful for the segregation and study of coagulation reactions. The protein is a single chain molecule comprised of 112 amino acids. This yields a calculated molecular weight of 12,028D. The calculated molecular weight and that which has been determined by sedimentation equilibrium analyses of the purified protein (12,500D) are in good agreement. A comparison of the amino acid sequence of CTI to that of other trypsin or serine protease inhibitors reveals little or no similarities. Extinction Coefficient (E1%1cm, 280nm): 20 Specific Activity: ~20u/mg Unit Definition: One unit is defined as the amount of CTI required to double the aPTT of 1ml normal human plasma. Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
Molecular Weight:
12500
Purity:
~95%(SDS-PAGE)
Form:
Supplied as a liquid in 20mM Tris, 150mM sodium chloride, pH 7.4.
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