title: Purification and amino acid sequence of Kunitz-type protease inhibitor found in the hemocytes of horseshoe crab (Tachypleus tridentatus).
abstract: A low molecular weight protein protease inhibitor was purified from Japanese horseshoe crab (Tachypleus tridentatus) hemocytes. It consisted of a single polypeptide with a total of 61 amino acid residues. This protease inhibitor inhibited stoichiometrically the amidase activity of trypsin (Ki = 4.60 X 10(-10) M), and also had inhibitory effects on alpha-chymotrypsin (Ki = 5.54 X 10(-9) M), elastase (Ki = 7.20 X 10(-8) M), plasmin, and plasma kallikrein. However, it had no effect on T. tridentatus clotting enzyme and factor C, mammalian blood coagulation factors (activated protein C, factor Xa and alpha-thrombin), papain, and thermolysin. The complete amino acid sequence of this inhibitor was determined and its sequence was compared with those of bovine pancreatic trypsin inhibitor (BPTI) and other Kunitz-type inhibitors. It was found that the amino acid sequence of this inhibitor has a high homology of 47 and 43% with those of sea anemone inhibitor 5-II and BPTI, respectively. Thus, this protease inhibitor appeared to be one of the typical Kunitz-type protease inhibitors.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Fukuoka.
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Hirai
authors.forename: F
authors.initials: F
authors.lastname: Tokunaga
authors.forename: S
authors.initials: S
authors.lastname: Kawabata
authors.forename: S
authors.initials: S
authors.lastname: Iwanaga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006737:Horseshoe Crabs; D007700:Kinetics; D010447:Peptide Hydrolases / Q000378:metabolism; D010455:Peptides; D010940:Plant Proteins; D011480:Protease Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D014361:Trypsin Inhibitors
chemical_list: C053865:Kunitz-type protease inhibitor, plant; D010455:Peptides; D010940:Plant Proteins; D011480:Protease Inhibitors; D014361:Trypsin Inhibitors; D010447:Peptide Hydrolases