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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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Journal ArticleDOI
TL;DR: In the three cases, nifH is followed by two ORF (open reading frames) similar to ORF105 and ORF128 respectively, which were previously found downstream of Methanococcus thermolithotrophicus n ifH.

35 citations

Journal ArticleDOI
TL;DR: The purified oxygen-stable enzymes catalyzed the oxidation of 5,10-methylenetetrahydromethanopterin and methyltet Brahmanopterin with Vmax values of 3000 and 200 mumol min-1 mg-1, respectively.

35 citations

Journal ArticleDOI
TL;DR: Redox titrations at different pH values demonstrated that the proximal cluster and one of the clusters in the EchF subunit had a pH-dependent midpoint potential and the possible relevance of these properties for the function of this proton-pumping [NiFe]-hydrogenase is discussed.
Abstract: The purified membrane-bound [NiFe]-hydrogenase from Methanosarcina barkeri was studied with electron paramagnetic resonance (EPR) focusing on the properties of the iron-sulphur clusters. The EPR spectra showed signals from three different [4Fe-4S] clusters. Two of the clusters could be reduced under 101 kPa of H2, whereas the third cluster was only partially reduced. Magnetic interaction of one of the clusters with an unpaired electron localized on the Ni-Fe site indicated that this was the proximal cluster as found in all [NiFe]-hydrogenases. Hence, this cluster was assigned to be located in the EchC subunit. The other two clusters could therefore be assigned to be bound to the EchF subunit, which has two conserved four-Cys motifs for the binding of a [4Fe-4S] cluster. Redox titrations at different pH values demonstrated that the proximal cluster and one of the clusters in the EchF subunit had a pH-dependent midpoint potential. The possible relevance of these properties for the function of this proton-pumping [NiFe]-hydrogenase is discussed.

35 citations

Journal ArticleDOI
TL;DR: Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same.
Abstract: Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H2-CO2, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 μmol of acetate per mmol of CH4 formed, but M. mazei produced only 8 to 9 μmol of acetate per mmol of CH4.

35 citations

Journal ArticleDOI
TL;DR: The membrane-associated coenzyme F420-reactive hydrogenase of the anaerobic methanogenic archaeon Methanosarcina barkeri Fusaro has been purified 95-fold to apparent homogeneity and the amino acid sequence PXXRXEGH, where X is any amino acid, was found to be conserved in the N-termini of the putative nickel-binding subunits of most [NiFe]- and [Ni FeSe]hydrogenases.
Abstract: The membrane-associated coenzyme F420-reactive hydrogenase of the anaerobic methanogenic archaeon Methanosarcina barkeri Fusaro has been purified 95-fold to apparent homogeneity. A new purification procedure and altered storage conditions gave substantially higher yield (13.4% versus 4.3%) and specific coenzyme F420-reducing activity (82.8 μmol · min−1· mg protein−1 versus 11.5 μmol · min−1· mg protein−1) than reported previously [Fiebig, K. & Friedrich, B. (1989) Eur. J. Biochem. 184, 79–88]. The predominant coenzyme F420-reactive form of the hydrogenase has an apparent molecular mass of 198 kDa and is composed of three non-identical subunits with apparent molecular masses of 48 (α), 33 (β), and 30 kDa (γ), apparently in a stoichiometry of α2β2γ1. This minimal coenzyme F420-reducing hydrogenase formed aggregates with apparent molecular masses of approximately 845 kDa. 1 mol of the 198-kDa form of hydrogenase contained 2 mol FAD, 2 mol nickel, 28–32 mol non-heme iron, and 34 mol acid-labile sulfur; in addition, 0.2 mol selenium was detected. The isoelectric point was 5.30. The amino acid sequence PXXRXEGH, where X is any amino acid, was found to be conserved in the N-termini of the putative nickel-binding subunits of most [NiFe]- and [NiFe]Sehydrogenases of methanogenic Archaea and Bacteria. However, this motif was not detected in the protein sequences of [Fe]hydrogenases. Maximal coenzyme F420-reducing activity was obtained with reductively reactivated enzyme at 55°C in the pH range 6.5–7.25. The Km, values of the purified enzyme for H2 with coenzyme F420 or methylviologen as electron acceptor were extremely low, namely 3μM and 4μM. The catalytic efficiency coefficients (kcat/Km) for H2 with both reducible cosubstrates were high: 2.5×107M−1· s−1 with coenzyme F420 and 6.9×107 M−1· S−1 with methylviologen.

34 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202212
202112
202012
20197
201818