Kunitz-type proteinase inhibitors derived by limited proteolysis of the inter-alpha-trypsin inhibitor, V. Attachments of carbohydrates in the human urinary trypsin inhibitor isolated by affinity chromatography.

The inhibitory active part of the inter-alpha-trypsin inhibitor with a known amino acid sequence is present as an acid-resistant inhibitor in human serum, in urine, in bronchial and in nasal mucus. The inhibitor molecule has a 50% carbohydrate content. Carbohydrate side chains are attached in two positions. One chain is linked to the polypeptide O-glycosidically via the serine residue in position 10 in the N-terminal extension peptide. The second side chain is attached N-glycosidically via the asparagine residue in position 24, located in the inactive "inhibitory" Kunitz-type domain of the inhibitor. The composition of the carbohydrate side chains were determined.