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  • 1
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of methyl-coenzyme M reductase in Methanobacterium thermoautotrophicum (1987)
    Springer
    Archives of microbiology 147 (1987), S. 190-194 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Methyl-CoM reductase ; Immunocytochemistry ; Colloidal gold ; Energy conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells of Methanobacterium thermoautotrophicum were fixed with glutaraldehyde, sectioned and labeled with antibodies against the β subunit of component C (=methyl-CoM reductase) of methyl-CoM reductase system and with colloidal gold-labeled protein A. It was found that the gold particles were located predominantly in the vicinity of the cytoplasmic membrane, when the cells were grown under conditions where methyl-CoM reductase was not overproduced. This finding confirms the recent data obtained with Methanococcus voltae showing via the same immunocytochemical localization technique that in this organism methyl-CoM reductase is membrane associated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00415283
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Monensin and gramicidin stimulate CH4 formation from H2 and CO2 in Methanobacterium thermoautotrophicum at low external Na+ concentration (1986)
    Springer
    Archives of microbiology 146 (1986), S. 181-185 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Na+ dependent methanogenesis ; Na+/H+ antiporter ; Monensin ; Gramicidin ; Uncoupler
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methane formation from H2 and CO2 in methanogenic bacteria is a Na+-dependent process. In this communication the effects of Na+ ionophores, of uncouplers, and of Na+/H+ antiporter inhibitors on methane formation from H2 and CO2 were studied with Methanobacterium thermoautotrophicum. 1. Na+ ionophores (the Na+/H+ antiporters monensin and lasalocid and the Na+ uniporter gramicidin) stimulated methanogenesis at lwo external Na+ concentrations when the K+ concentration was high. The ionophores had no effect at high external Na+ concentrations and were inhibitory at low external K+ concentrations. 2. Uncouplers (protonophores and valinomycin plus K+) inhibited methanogenesis at low external Na+ concentration at both low and high external K+ concentrations. Inhibition by uncouplers was relieved by the addition of either Na+ or Na+ ionophores. 3. Na+/H+ antiporter inhibitors (harmaline, amiloride, and NH 4 + ) inhibited methanogenesis at low external Na+ concentration. Inhibition was relieved by the addition of either Na+ or of the Na+ ionophores. The results are discussed with respect to the role of Na transport across the cytoplasmic membrane in methanogenesis from H2 and CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402348
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Testing the “methanochondrion concept”: are nucleotides transported across internal membranes in Methanobacterium thermoautotrophicum? (1987)
    Springer
    Archives of microbiology 146 (1987), S. 370-376 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Nucleotide transport ; Nucleotide binding ; Protoplasts ; Membrane vesicles ; Methanochondrion concept
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to test the “Methanochondrion concept”, uptake of adenine nucleotides in various membrane preparations of Methanobacterium thermoautotrophicum was studied. The uptake showed properties which are in general interpreted as indicative of a transport mechanism: (i) kinetics in the time range of minutes, (ii) temperature dependence, (iii) substrate specificity and (iv) failure to remove the substrate by extensive washing. However, nucleotide transport as an interpretation of this “uptake” can definitely be excluded. Not only an exchange mechanism of the mitochondrial type, but also a general exchange or an uniport mechanism was ruled out. In contrast, the “nucleotide uptake” was shown to be actually a tight and specific binding of ADP and ATP to binding sites at the interior side of the cell membrane. This was conclusively demonstrated in protoplasts obtained from M. thermoautotrophicum cells. In these protoplasts which do not contain internal membranes also nucleotide binding was observed, but only after disruption of the plasma membrane by osmotic lysis, which leads to the exposure of binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410938
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  • 4
    Electronic Resource
    Electronic Resource
    ATP formation coupled to caffeate reduction by H2 in Acetobacterium woodii NZva16 (1988)
    Springer
    Archives of microbiology 150 (1988), S. 447-451 
    Details
    ISSN: 1432-072X
    Keywords: Acetobacterium woodii ; Caffeate reduction ; ATP formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have addressed the question, whether the reduction of caffeate in Acetobacterium woodii strain NZva16 is coupled to ATP synthesis by electron transport phosphorylation. The following results were obtained: 1. Cultures of A. woodii with H2 and CO2, grew to greater cell densities, when caffeate was also present. Caffeate was reduced to give hydrocaffeate and less acetate was formed. The cell yield based on the amount of caffeate reduced was approximately 1 g dry cells/mol. 2. Non-growing bacterial suspensions catalyzed the reduction of caffeate by H2. The specific activity (0.2–1.0 μmol · min−1 · mg−1 bacterial protein) was as high as expected for a catabolic reaction. 3. The ATP content of bacteria incubated, with H2 increased from 〈 1 to about 7 μmol per g cellular protein on the addition of caffeate. The ATP yield was calculated as 0.06 mol ATP · mol−1 caffeate from the initial velocity of ATP formation and the activity of caffeate reduction. Valinomycin together with nigericin inhibited ATP formation and caused a 2–3-fold increase of the activity of caffeate reduction. Protonophores were without, effect. 4. Caffeate in the presence of H2 caused the uptake of tetraphenylphosphonium cation by the bacteria. The uptake was abolished by valinomycin plus nigericin, and was considerably enhanced by monensin. Protonophores were without effect, even in the presence of monensin. It is concluded that caffeate reduction by H2 is coupled to ATP formation by electron transport phosphorylation. However, the failure of protonophores to prevent phosphorylation and TPP uptake cannot be explained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422285
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    Paper (German National Licenses)
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