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Methanosarcina barkeri
About: Methanosarcina barkeri is a research topic. Over the lifetime, 703 publications have been published within this topic receiving 32151 citations.
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TL;DR: Dimethylamine:5-hydroxybenzimidazolylcobamide methyltransferase was purified from cells of Methanosarcina barkeri Fusaro grown on trimethylamin and incubation with these compounds resulted in the methylation of the corrinoid prosthetic group.
Abstract: Dimethylamine : 5-hydroxybenzimidazolylcobamide methyltransferase (DMA-MT) was purified from cells of Methanosarcina barkeri Fusaro grown on trimethylamine. In the presence of methylcobalamine :coenzyme M methyltransferase isoenzyme II [MT2(II)] the enzyme quite specifically catalyzed the stoichiometric conversion of dimethylamine (apparent Km = 0.45 mM) and 2-mercaptoethanesulfonate (coenzyme M) to monomethylamine and methyl-coenzyme M. Monomethylamine was a competitive inhibitor of the reaction (Ki = 4.5 mM). The apparent molecular mass of DMA-MT was 100 kDa and the enzyme was found to be a dimer, composed of identical 50-kDa subunits. A corrinoid content of 0.9 ± 0.1 mol B12/mol holoenzyme was calculated from HPLC analysis. The as-isolated methyltransferase was inactive, but it could be reductively reactivated. Activation required the presence of methyltransferase-activating protein, ATP and dimethylamine. Incubation with these compounds resulted in the methylation of the corrinoid prosthetic group.
20 citations
TL;DR: Methods and antibody probes were developed to elucidate the configurtion of antigens' and archaebacteria's surfaces and to find markers of scientific (evolutionary) and practical (biotechnologic) interest.
20 citations
TL;DR: The Co-methyl and the Co-aquo derivative of 5-hydroxybenzimidazolylcobamide (factor III) were isolated as the major natural corrinoids from Methanosarcina barkeri 'Fusaro' as mentioned in this paper.
20 citations
TL;DR: Heterologous aminoacylation of tRNA with high selectivity for Archaebacterial tRNA and substrate properties of ATP analogues reveals a unique pattern, reflecting the supposed genealogical difference between the urkingdoms of archaebacteria, eubacteria, and eukaryotes.
20 citations
TL;DR: Reductive carboxylation of a triose precursor (derived from pyruvate) to synthesize erythrose 4-phosphate is consistent with the labeling patterns observed in phenylalanine and ribose.
Abstract: NMR spectroscopy was used to determine the labeling patterns of the ribose moieties of ribonucleosides purified from Methanospirillum hungatei, Methanococcus voltae, Methanobrevibacter smithii, Methanosphaera stadtmanae, Methanosarcina barkeri and Methanobacterium bryantii labeled with 13C-precursors. In most methanogens tested ribose was labeled in a manner consistent with the operation of the oxidative branch of the pentose phosphate pathway. In contrast, transaldolase and transketolase reactions typical of a partial nonoxidative pentose phosphate pathway are hypothesized to explain the different labeling patterns and enrichments of carbon atoms observed in the ribose moiety of Methanococcus voltae. The source of erythrose 4-phosphate needed for the transaldolase reaction proposed in Methanococcus voltae, and for biosynthesis of aromatic amino acids in methanogenic bacteria in general, was assessed. Phenylalanine carbon atom C-7 was labeled by [1-13C]pyruvate in Methanospirillum hungatei, Methanococcus voltae, and Methanococcus jannaschii, the only methanogens which incorporated sufficient label from pyruvate for testing. Reductive carboxylation of a triose precursor (derived from pyruvate) to synthesize erythrose 4-phosphate is consistent with the labeling patterns observed in phenylalanine and ribose.
20 citations