title: Isolation of novel peptides, cabin-1, -2, -3, and -4, that inhibit cathepsin B from a thermolysin digest of human plasma.
abstract: Four novel peptides that inhibit cathepsin B, designated as Cabin-1, -2, -3, and -4, were isolated from a thermolysin digest of human plasma. After gel filtration and cation-exchange chromatography, the peptide mixture was purified by reverse-phase HPLC to isolate Cabin-1, -2, -3, and 4, with the amino acid sequences LGPVTQE, VLQSSGLYS, VVSVLT, and LVYDAY, respectively. These peptides correspond to f(64-70) of human apolipoprotein A-I for Cabin-1, f(56-64) and f(185-190) of the human immunoglobulin G gamma chain for Cabin-2 and -3, and f(66-71) of human transferrin for Cabin-4. Synthetic Cabin-1, -2, -3, and -4 showed dose-dependent inhibition of cathepsin B. Their IC50 values were 450, 500, 20, and 5.0 micromol/l, respectively. Lineweaver-Burk plots suggested that Cabin-3 is a noncompetitive inhibitor, while Cabin-4 is a competitive inhibitor. Among the N- and C-terminal deletion peptides of Cabin-2 and -4, Cabin-2(1-8), VLQSSGLY, was found to have the most potent inhibitory activity, with an IC50 of 3.8 micromol/l.
authors.affiliation: Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan. nakagomi@pharm.teikyo-u.ac.jp
authors.forename: Kazuya
authors.initials: K
authors.lastname: Nakagomi
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Fujimura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Maeda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sadakane
authors.forename: Noriko
authors.initials: N
authors.lastname: Fujii
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Akizawa
authors.forename: Takenori
authors.initials: T
authors.lastname: Tanimura
authors.forename: Yasumaru
authors.initials: Y
authors.lastname: Hatanaka
mesh_terms: D002401:Cathepsin B / Q000037:antagonists & inhibitors* / Q000097:blood; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007700:Kinetics; D013058:Mass Spectrometry; D009842:Oligopeptides / Q000302:isolation & purification / Q000494:pharmacology*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010949:Plasma / Q000737:chemistry*; D013820:Thermolysin / Q000737:chemistry*
chemical_list: D009842:Oligopeptides; D010455:Peptides; C468309:cabin-1; C468308:cabin-2; C468307:cabin-3; C468306:cabin-4; D002401:Cathepsin B; D013820:Thermolysin