title: A serine proteinase of an archaebacterium, Halobacterium mediterranei. A homologue of eubacterial subtilisins.
abstract: A homogeneous serine proteinase secreted by the extreme halophilic bacterium Halobacterium mediterranei 1538 was isolated by affinity chromatography on bacitracin-Sepharose with a yield of 48% (260-fold purification). The enzyme reveals an optimum for pyroglutamyl-Ala-Ala-Leu p-nitroanilide hydrolysis at pH 8.0-8.5 (Km 0.14 mM; k(cat). 36.9 s-1). Its activity increases linearly with NaCl concentration over the range 2-5 M. The substrate specificity of the enzyme is comparable with that of secretory subtilisins, the extent of protein degradation approaching that attained with proteinase K. The enzyme has a molecular mass of 41 kDa and a pI of 7.5. The N-terminal sequence of H. mediterranei serine proteinase reveals a 50% identity with that of Thermoactinomyces vulgaris serine proteinases, indicating that the enzyme belongs to the subtilisin family. Hence the serine proteinase secreted by the halophilic bacterium should be considered as a functional analogue, and a structural homologue, of eubacterial serine proteinases (subtilisins).
authors.affiliation: Institute of Genetics and Selection of Industrial Micro-organisms, Moscow, Russia.
authors.forename: V M
authors.initials: VM
authors.lastname: Stepanov
authors.forename: G N
authors.initials: GN
authors.lastname: Rudenskaya
authors.forename: L P
authors.initials: LP
authors.lastname: Revina
authors.forename: Y B
authors.initials: YB
authors.lastname: Gryaznova
authors.forename: E N
authors.initials: EN
authors.lastname: Lysogorskaya
authors.lastname: Filippova IYu
authors.forename: I I
authors.initials: II
authors.lastname: Ivanova
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001419:Bacteria / Q000201:enzymology; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006217:Halobacterium / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D013381:Subtilisins / Q000235:genetics
chemical_list: D000596:Amino Acids; D012697:Serine Endopeptidases; D013381:Subtilisins