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Methanosarcina barkeri has recently been shown to produce a multisubunit membrane-bound [NiFe] hydrogenase designated Ech (Escherichia coli hydrogenase 3) hydrogenase. In the present study Ech hydrogenase was purified to apparent homogeneity in a high yield. The enzyme preparation obtained only contained the six polypeptides which had previously been shown(More)
Efficient methods of processing unanticipated queries are a crucial prerequisite for the success of generalized database management systems. A wide variety of approaches to improve the performance of query evaluation algorithms have been proposed: logic-based and semantic transformations, fast implementations of basic operations, and combinatorial or(More)
It was recently reported that the extreme thermophile Methanopyrus kandleri contains only a H2-forming N5,N10-methylenetetrahydromethanopterin dehydrogenase which uses protons as electron acceptor. We describe here the presence in this Archaeon of a second N5,N10-methylenetetrahydromethanopterin dehydrogenase which is coenzyme F420-dependent. This enzyme(More)
Benzoyl-coenzyme A is the most common central intermediate of anaerobic aromatic metabolism. Studies with whole cells of different bacteria and in vitro had shown that benzoyl-CoA is reduced to alicyclic compounds, possibly via cyclohexadiene intermediates. This reaction is considered a 'biological Birch reduction'. We have elucidated by NMR techniques the(More)
The enzymes catalyzing the initial reactions in the anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) were studied with a denitrifying Pseudomonas sp. anaerobically grown with 2-aminobenzoate and nitrate as the sole carbon and energy sources. Cells grown on 2-aminobenzoate are simultaneously adapted to growth with benzoate, whereas cells grown(More)
Social behavior in the bacterium Myxococcus xanthus relies on contact-dependent activities involving cell-cell and cell-substratum interactions. To identify outer membrane proteins that have a role in these activities, we profiled the outer membrane proteome of growing and starving cells using two strategies. First, outer membrane proteins were enriched by(More)
The genes hdrA, hdrB and hdrC, encoding the three subunits of the iron-sulfur flavoprotein heterodisulfide reductase, have been cloned and sequenced. HdrA (72.19 kDa) was found to contain a region of amino acid sequence highly similar to the FAD-binding domain of pyridine-nucleotide-dependent disulfide oxidoreductases. Additionally, 110 amino acids(More)
Different anaerobic bacteria can oxidize a variety of aromatic compounds completely to CO2 via one common aromatic intermediate, benzoyl-CoA. It has been postulated that anaerobically the aromatic nucleus of benzoyl-CoA becomes reduced. An oxygen-sensitive enzyme system is described catalyzing the reduction of benzoyl-CoA to(More)
The methylviologen-reducing hydrogenase operon of Methanobacterium thermoautotrophicum contains an open reading frame, mvhB, the product of which was predicted to have a molecular weight of 44 kDa and to contain as many as 48 iron atoms in 12 [4Fe-4S] clusters, and was therefore suggested to be a polyferredoxin. We have now, for the first time, isolated(More)
Cell-free extracts of Pseudomonas sp. strains KB 740 and K 172 both contained high levels of glutaryl-CoA dehydrogenase when grown anaerobically on benzoate or other aromatic compounds and with nitrate as electron acceptor. These aromatic compounds have in common benzoyl-CoA as the central aromatic intermediate of anaerobic metabolism. The enzymatic(More)