title: Purification and characterization of cathepsin L from the white muscle of chum salmon, Oncorhynchus keta.
abstract: 1. Cathepsin L of the white muscle of chum salmon (Oncorhynchus keta) in spawning migration was purified to homogeneity by a series of chromatography on DEAE-Sephadex (1st), SP-Sephadex, CM-Sephadex, DEAE-Sephadex (2nd) and Sephadex G-100. 2. The molecular weight of salmon muscle cathepsin L was estimated to be 30,000 and its isoelectric point was 5.2. 3. Cathepsin L had a pH optimum of 5.6, required a thiol-reducing reagent for activation, and was inhibited by cysteine protease inhibitors. 4. The Km and kcat values for Z-Phe-Arg-MCA were determined to be 1.68 microM and 15.8 s-1, respectively. This enzyme hydrolyzed proteins such as insulin B chain, hemoglobin, serum albumin and azocasein easily. 5. The bond specificity to oxidized insulin B chain inferred that the enzyme had a preference for hydrophobic amino acid in P2 and P3 residues.
authors.affiliation: National Research Institute of Fisheries Science, Tokoyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamashita
authors.forename: S
authors.initials: S
authors.lastname: Konagaya
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002645:Chickens; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D004792:Enzyme Precursors / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D051381:Rats; D012474:Salmon / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D000596:Amino Acids; D004792:Enzyme Precursors; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534280:Ctsl protein, rat