Thermophiles hydrogenases

Juszczak A, S Aono, MWW Adams (1991) The extremely thermophilic eubacterium Thermotoga maritima, contains a novel iron-hydrogenase whose cellular activity is dependent upon tungsten. J Biol Chem 266 13834-13841. 

Laska S, F Lottspeicht, A Kletzin (2003) Membrane-bound hydrogenase and sulfur reductase of the hyper-thermophilic and acidophilic archaeon AcidiawMi ambivalens. Microbiology (UK) 149 2357-2371. 

Ma, K., Schicho, R. N., Kelly, R. M. and Adams, M. W. W. (1993) Hydrogenase of the hyper-thermophile Pyrococcus furiosus is an elemental sulfur reductase or sulfhydrogenase Evidence for a sulfur-reducing hydrogenase ancestor. Proc. Natl. Acad. Sci. USA, 90, 5341-4. 

Kletzin A. 1994. Sulfur oxidation and reduction in Archaea— sulfur oxygenase/reductase and hydrogenase from the extremely thermophilic and facultatively anaerobic archaeon Desulfurolobus ambivalens. Syst Appl Microbiol 16 534-43. 

In Thermotoga maritima, the most thermophilic organism known, tungsten promotes synthesis of an Fe-contain-ing hydrogenase as well as some other enzymes but seems to have a regulatory rather than a structural role.688... 

A relatively simple and quick procedure for the isolation of Photosystem I-enriched particles from the thermophilic cyanobacterium Phormidium laminosum, without the use of detergents for solubilization, is described. The procedure involves sonication of cells, centrifugation and DEAE-cellulose chromatography. The particles had an 02 uptake activity of up to 200 pmol 02. mg chlorophyll h 1 and appeared as vesicles of 200 100 nm diameter when observed under electron microscopy. The analysis of the chlorophyll-protein complexes by polyacrylamide gel electrophoresis showed that these particles are enriched in the complexes associated with Photosystem I and partially depleted in those associated with Photosystem II. The particles did not contain ferredoxin and were active in NADP-photoreduction only in the presence of added ferredox in. They were also able to photoreduce externally added electron mediators using ascorbate as electron donor, the reduced mediators can be coupled to hydrogenase for the production of H2 or for the activation of cyanobacterial phosphoribulokinase using a ferredoxin/thioredoxin system. 

In this paper we describe an easy, reproducible, and fast procedure for obtaining PSI-enriched particles by a non-detergent method from the thermophilic cyanobacterium Phormidium lamirtosum. These particles showed a PSI activity (ascorbate/DCPIP MV) of up to 200 (imole 02 taken up per mg chlorophyll per h, and negligible PSII activity (H20 DMBQ or ferricyanide). We also present evidence on the feasibility of H2 photoproduction and phosphoribulokinase photoactivation mediated by such PSI particles coupled to hydrogenase or to a Fd/TRX system. 

Aerobic bacteria such as Azotobacter vinelandii, Alcaligenes eutrophus, and Nocardia opaca, and facultative anaerobes, such as Escherichia coli and various species of Rhizobium and Bradyrhizobium (the symbionts of leguminous plants), also contain hydrogenase, as do photosynthetic bacteria such as Chromatium vinosum, Rhodobacter capsulatus (formerly Rhodopseudomonas capsulata), and Anabaena variabilis (a filamentous cyanobacterium). The thermophilic hydro-... 

Enzyme and whole cell activities of the thermophile Thermotoga maritima were examined for comparison with and complementation of the recombinant enzymes and the Pyrococcus hydrogenase. 

The methyl viologen-reducing activity of hydrogenase in crude extracts from the deep-sea thermophile Methanococcus jannaschii was assayed using the high-pressure, high-temperature reactor system shown in Fig. 1. The reaction vessel... 

Pyrococcus endeavori (unpublished results ), hydrogenases from Methanococcus jannaschii and the extreme thermophile Methanococcus igneus, a-glucosidase from P. furiosus, glyceraldehyde-3-phosphate dehydrogenase from Thermotoga... 

For example, a ferredoxin hydrogenase (EC 1.12.7.2) has been isolated recently from the hyperthermophile Pyrococcus fUriosus [38]. The performance of this biocatalyst, which showed a remarkable stability under operative conditions, has been investigated for the NADPH regeneration in the reduction of prochiral ketones catalyzed by the thermophilic NADPH-dependent ADH from Thermoanaerohium sp. Total turnover numbers (TTNs mole product/mole consumed cofactor NADP" ") of 100 and 160 could be estimated in the reduction of acetophenone and (2S)-hydroxy-l-phenyl-propanone, respectively. As a side note, it should be mentioned that, although the activity of the P. furiosus hydrogenase increased exponentially with temperature up to its maximum above 80 °C, the reactions had to be performed at much lower temperature (40 °C) because of the thermal instability of NADPH. 

SRBs reduce sulfate to sulfide, which usually shows up as hydrogen sulfide or, if iron is available, as black ferrous sulfide (Fig. 10.10). In the absence of sulfate, some strains can function as fermenters and use organic compounds such as pyruvate to produce acetate, hydrogen, and carbon dioxide. Many SRB strains also contain hydrogenase enzymes, which allow them to consume hydrogen. Most common strains of SRB grow best at temperatures from 25 to 35°C. A few thermophilic strains capable of functioning efficiently at more than 60°C have been reported. 

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