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  • 1
    ISSN: 1433-4909
    Keywords: Key words Nucleoside diphosphate kinase ; Archaea ; Haloalkaliphiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ATP-binding protein from the haloalkaliphilic archaeon Natronobacterium magadii was purified and characterized by affinity chromatography on ATP-agarose and by fast protein liquid chromatography (FPLC) on a Mono Q column. The N-terminal 20 amino acid sequence of the kinase showed a strong sequence similarity of this protein with nucleoside diphosphate (NDP) kinases from different organisms and, accordingly, we believe that this protein is a nucleoside diphosphate kinase, an enzyme whose main function is to exchange γ-phosphates between nucleoside triphosphates and diphosphates. Comparison of the molecular weights of the NDP kinase monomer determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) (23 000) and of the oligomer determined by sedimentation equilibrium experiments (125 000) indicated that the oligomer is a hexamer. The enzyme was autophosphorylated in the presence of [γ-32P]ATP, and Mg2+ was required for the incorporation of phosphate. The kinase preserved the ability to transfer γ-phosphate from ATP to GDP in the range of NaCl concentration from 90 mM to 3.5 M and in the range of pH from 5 to 12. It was found and confirmed by Western blotting that this kinase is one of the proteins that bind specifically to natronobacterial flagellins. NDP kinase from haloalkaliphiles appeared to be simple to purify and to be a suitable enzyme for studies of structure and stability compared with NDP kinases from mesophilic organisms.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-4909
    Keywords: Key words Submarine hot vents ; Hyperthermophilic Archaea ; S-layers ; Immunochemical identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fourteen strains of hyperthermophilic organotrophic anaerobic marine Archaea were isolated from shallow water and deep-sea hot vents, and four of them were characterized. These isolates, eight previously published strains, and six type strains of species of the order Thermococcales were selected for the study of cell wall components by means of thin sectioning or freeze-etching electron microscopy. The cell envelopes of most isolates were shown to consist of regularly arrayed surface protein layers, either single or double, with hexagonal lattice (p6) symmetry, as the exclusive constituents outside the cytoplasmic membrane. The S-layers studied differed in center-to-center spacing and molecular mass of the constituent protein subunits. Polyclonal antisera raised against the cells of 10 species were found to be species-specific and allowed 12 new isolates from shallow water hot vents to be identified as representatives of the species Thermococcus litoralis, Thermococcus stetteri, Thermococcus chitonophagus, and Thermococcus pacificus. Of the 7 deep-sea isolates, only 1 was identified as a T. litoralis strain. Thus, hyperthermophilic marine organotrophic isolates obtained from deep-sea hot vents showed greater diversity with regard to their S-layer proteins than shallow water isolates.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4943
    Keywords: Archaebacteria ; flagella ofHalobacterium halobium ; domain structure ; unfolding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure ofHalobacterium halobium R1M1 flagella is investigated by the methods of scanning microcalorimetry, circular dichroism, and electron microscopy. It is shown that melting curves of flagella in solutions with a different concentration of NaCl display only one peak of heat capacity that corresponds to one cooperatively melting domain. It is found that flagella do not dissociate after melting. The possible structural organization of archaebacterial flagella is discussed.
    Type of Medium: Electronic Resource
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