title: Cathepsin L: a predominant heat-activated proteinase in arrowtooth flounder muscle.
abstract: Characterization of the autolytic profile of arrowtooth flounder (ATF) muscle indicated the involvement of heat-activated proteinases active at both acidic and alkaline pH values. Further assay of fish extract exhibited the maximum activity at 60 degrees C against casein used as a substrate at both pH 5.5 and 8.0. The maximum activity shifted to lower temperatures by the addition of urea with two distinctive patterns: activity reduction at pH 5.5 and activity enhancement at pH 8.0. The highest inhibition by E-64 indicated the proteinase belongs to the cysteine proteinase class. At pH 5.5, the proteinase hydrolyzed Z-Phe-Arg-NMec and all types of protein substrates tested at higher rate than that at pH 8.0. Activity bands, observed on the activity-stained substrate gels, indicated similar proteinases are responsible for the proteolytic activity observed at both pH values. When proteins of fish extract were separated by HPLC-SEC, only one proteolytic peak was observed at the retention time of 26 min with an estimated molecular weight of 39800 Da. The results implied cathepsin L is a predominant proteinase responsible for autolysis of ATF muscle at elevated temperatures.
authors.affiliation: BIOTEC Yothi-Research Unit, National Center for Genetic Engineering and Biotechnology, 73/1 NSTDA Building, Rama VI Road, Bangkok 10400, Thailand.
authors.forename: W
authors.initials: W
authors.lastname: Visessanguan
authors.forename: A R
authors.initials: AR
authors.lastname: Menino
authors.forename: S M
authors.initials: SM
authors.lastname: Kim
authors.forename: H
authors.initials: H
authors.lastname: An
mesh_terms: D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000378:metabolism*; D005432:Flounder; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D002403:Cathepsins; D010450:Endopeptidases; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L