Kunitz-type proteinase inhibitors derived by limited proteolysis of the inter-alpha-trypsin inhibitor, III. Sequence of the two Kunitz-type domains inside the native inter-alpha-trypsin inhibitor, its biological aspects and also of its cleavage products.

The human inhibitor HI-14 consists of two Kunitz-type domains covalently connected. They are liberated from the human ITI by limited tryptic proteolysis. The inhibitor HI-14 is formed via a trypsin inhibitor complex. We have reported the amino acid sequences of the domain with antitryptic activity and the homologous domain without activity. Here we present the sequence of the domains as present in ITI. The domain lacking antitryptic activity is the N-terminal part of the inhibitor HI-14, whereas the domain with antitryptic activity represents the C-terminal part of HI-14 and probably the C-terminus of the ITI-molecule, too.