Trypsin inhibitor III from squash seeds (Cucurbita maxima), its reactive site and proposed amino acid sequence

The amino acid sequence of trypsin inhibitor III isolated from squash seeds (Cucurbita maxima) was established by Edman degradation and standard enzymatic and chemical techniques. The inhibitor consists of 28 amino acids crosslinked by two disulfide bridges. Arginine in position 5 was shown to be present at the reactive site of the inhibitor.