title: Kunitz-type protease inhibitor found in rat mast cells. Purification, properties, and amino acid sequence.
abstract: A low molecular weight serine protease inhibitor, named trypstatin, was purified from rat peritoneal mast cells. It is a single polypeptide with 61 amino acid residues and an Mr of 6610. Trypstatin markedly inhibits blood coagulation factor Xa (Ki = 1.2 x 10(-10) M) and tryptase (Ki = 3.6 x 10(-10) M) from rat mast cells, which have activities that convert prothrombin to thrombin. It also inhibits porcine pancreatic trypsin (Ki = 1.4 x 10(-8) M) and chymase (Ki = 2.4 x 10(-8) M) from rat mast cells, but not papain, alpha-thrombin, or porcine pancreatic elastase. Trypstatin forms a complex in a molar ratio of 1:1 with trypsin and one subunit of tryptase. The complete amino acid sequence of this inhibitor was determined and compared with those of Kunitz-type inhibitors. Trypstatin has a high degree of sequence homology with human and bovine inter-alpha-trypsin inhibitors, A4(751) Alzheimer's disease amyloid protein precursor, and basic pancreatic trypsin inhibitor. However, unlike other known Kunitz-type protease inhibitors, it inhibits factor Xa most strongly.
authors.affiliation: Division of Enzyme Chemistry, University of Tokushima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kido
authors.forename: Y
authors.initials: Y
authors.lastname: Yokogoshi
authors.forename: N
authors.initials: N
authors.lastname: Katunuma
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000302:isolation & purification*; D011506:Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012689:Sequence Homology, Nucleic Acid; D015842:Serine Proteinase Inhibitors; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000494:pharmacology; D014361:Trypsin Inhibitors / Q000494:pharmacology
chemical_list: D011480:Protease Inhibitors; D011506:Proteins; D015842:Serine Proteinase Inhibitors; D014361:Trypsin Inhibitors; D014360:Trypsin Inhibitor, Kunitz Soybean