A serine proteinase of an archaebacterium, Halobacterium mediterranei. A homologue of eubacterial subtilisins.
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).
Stepanov
V M
VM
Institute of Genetics and Selection of Industrial Micro-organisms, Moscow, Russia.
Rudenskaya
G N
GN
Revina
L P
LP
Gryaznova
Y B
YB
Lysogorskaya
E N
EN
Filippova IYu
Ivanova
I I
II
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
D000596:Amino Acids; D012697:Serine Endopeptidases; D013381:Subtilisins