title: A halophilic extracellular protease from a halophilic archaebacterium strain 172 P1.
abstract: An unidentified halophilic archaebacterium strain 172 P1 produced three extracellular proteases in media containing 15-27% salts. One component, F-II, was purified to homogeneity. It is a serine protease that can be inhibited by phenylmethylsulfonyl fluoride and chymostatin. A high concentration of NaCl was required for its stability; in the presence of 25% NaCl, only 4% of the activity was lost by incubating at 60 degrees C for 30 min, while complete inactivation occurred in the presence of 5% NaCl. F-II is a thermophilic and halophilic protease. High activity was obtained at 75-80 degrees C when F-II was assayed in the presence of 25% NaCl. The optimal concentration of NaCl required was 10-14% when assayed at 70 degrees C with azocasein as substrate, though a halophilic characteristic was not distinct at lower temperatures. Hydrolyses of the synthetic substrates succinyl-alanyl-alanyl-prolyl-phenylalanyl-4-methylcoumaryl-7-amide or succinyl-alanyl-alanyl-alanyl-p-nitroanilide at 26 degrees C were maximal at 25 and 30% NaCl, respectively. F-II was most stable at pH 6-7, and its optimal pH was 10.7. Its molecular weight was estimated as 44,000-46,000 by sodium dodecyl sulfate--polyacrylamide gel electrophoresis and by gel filtration--high-pressure liquid chromatography. The sequence of the 35 N-terminal amino acid residues was determined and compared with that of other serine proteases.
authors.affiliation: Noda Institute for Scientific Research, Chiba-ken, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kamekura
authors.forename: Y
authors.initials: Y
authors.lastname: Seno
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000201:enzymology*; D001419:Bacteria / Q000201:enzymology*; D002845:Chromatography / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D011480:Protease Inhibitors; D012965:Sodium Chloride; D010447:Peptide Hydrolases