Abstract
A heat stable trypsin inhibitor was found in the bran of soft-shelled job's-tears (Coix lacrymajobi L. var. Ma-yuen Stapf) seeds. This inhibitor seemed to be a simple protein, and the molecular weight was about 12, 000. Similar to other heat stable trypsin inhibitors, this inhibitor also contained many cysteine or cystine residues in the molecule. This inhibitor inhibited bovine trypsin at the molar ratio of 1 to 2, showing that it was double-headed. Its activity was stable against the change of pH at the range of 3 to 11 and high temperature of 100°C under certain conditions. However, the degree of heat stability of the inhibitory activity depended highly upon the kind of the solution in which this inhibitor was dissolved.
