title: Purification and characterization of myofibril-bound serine protease from lizard fish (Saurida undosquamis) muscle.
abstract: Myofibril-bound serine protease (MBSP) from lizard fish (SAURIDA UNDOSQUAMIS: Synodontidae) skeletal muscle was purified to homogeneity with higher purification (1260-fold) and higher recovery (7%) than our previous report in lizard fish (Saurida wanieso). The new purification method combines a heat-treatment for dissociation from washed myofibrils, acid-treatment at pH 5.0 before and after lyophilization, and alcohol-treatment, followed by two column chromatographies. The molecular mass of the enzyme was estimated to be 50 kDa under non-reducing conditions and 28 kDa under reducing conditions by SDS-PAGE. The N-terminal amino acid sequence of the MBSP was determined to be 22 residues (IVGGYEXEAYSKPYQVSINLGY) and the sequence showed high homology to carp and other fish trypsins (64-77%), but did not show high homology to carp MBSP (41%). The enzyme activity was inhibited by serine protease inhibitors such as Pefabloc SC, leupeptin, TLCK and native protein inhibitors (soybean trypsin inhibitor, alpha(1)-antitrypsin and aprotinin). The purified enzyme specifically hydrolyzed at the carboxyl side of the arginine residue of synthetic 4-methyl-coumaryl-7-amide substrate. When purified MBSP was stored at -35 degrees C in the presence of 50% ethylene glycol (V/V), the enzyme activity was entirely preserved over 6 months and stable against freezing and thawing. Activities for both casein and the synthetic substrate were most active at pH 9.0, and the enzyme was most active approximately 55 degrees C with casein and between 35 and 45 degrees C for synthetic substrate. When myofibrils were incubated with purified MBSP, myosin heavy chain was mostly degraded approximately 55 degrees C, but the degradation of actin was very slow.
authors.affiliation: Graduate School of Science and Technology, Nagasaki University, Bunkyo, Nagasaki 852-8521, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohkubo
authors.forename: Kourin
authors.initials: K
authors.lastname: Miyagawa
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Osatomi
authors.forename: Kenji
authors.initials: K
authors.lastname: Hara
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Nozaki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishihara
mesh_terms: D000818:Animals; D005399:Fishes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology*; D009210:Myofibrils / Q000201:enzymology / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D010446:Peptide Fragments; D012697:Serine Endopeptidases