Merck

Tungsten-containing enzymes.

Biochemistry. Biokhimiia (2002-04-16)
N P L'vov, A N Nosikov, A N Antipov
ABSTRACT

The biological importance of tungsten has been fully proved in the last decade due to isolation of a number of tungsten-containing enzymes (W-enzymes) from hyperthermophilic archaea. Tungsten was previously considered only as an antagonist of molybdenum, because the replacement of molybdenum by tungsten (due to their chemical similarity) leads to inactivation of molybdenum-containing enzymes (Mo-enzymes). In addition to the "true W-enzymes" in which tungsten cannot be replaced by molybdenum, recently some enzymes have been isolated which can use either molybdenum or tungsten in the catalytic process. This review briefly summarizes data on the participation of tungsten in catalysis by some enzymes and the structure of the active sites of W-enzymes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
钨, wire, diam. 0.25 mm, ≥99.9% trace metals basis
Sigma-Aldrich
钨, foil, thickness 0.05 mm, ≥99.9% trace metals basis
Sigma-Aldrich
钨, wire, diam. 0.5 mm, ≥99.9% trace metals basis
Sigma-Aldrich
钨, wire, diam. 1.0 mm, 99.99% trace metals basis
Sigma-Aldrich
钨, foil, thickness 0.25 mm, ≥99.9% trace metals basis
钨, mesh, 50x50mm, nominal aperture 0.2mm, wire diameter 0.05mm, 100 wires/inch, open area 64%, plain weave mesh, 99.95%
Sigma-Aldrich
钨, foil, thickness 0.127 mm, ≥99.9% trace metals basis
钨, wire reel, 5m, diameter 0.005mm, gold plated, 99.95%
Sigma-Aldrich
钨, foil, thickness 0.5 mm, ≥99.9% trace metals basis
钨, wire reel, 25m, diameter 0.05mm, clean, 99.95%
钨, foil, light tested, 100x100mm, thickness 0.05mm, as rolled, 99.95%
钨, lump, 50g, max. size 5mm
钨, wire, straight, 300mm, diameter 0.10mm, 99.9+%
钨, rod, 100mm, diameter 1.6mm, centerless ground, 99.95%
钨, wire reel, 10m, diameter 0.5mm, clean, 99.95%
钨, wire, straight, 1000mm, diameter 0.30mm, 99.9+%
钨, wire, straight, 300mm, diameter 0.25mm, 99.9+%
钨, wire reel, 25m, diameter 0.15mm, clean, 99.95%
钨, wire reel, 25m, diameter 0.1mm, clean, 99.95%
钨, insulated wire, 1m, conductor diameter 0.075mm, insulation thickness 0.02mm, PTFE (polytetrafluoroethylene) insulation, 99.9%
钨, foil, 100x100mm, thickness 0.125mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 0.15mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 0.1mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 0.2mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 0.3mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 0.5mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 1.0mm, as rolled, 99.95%
钨, foil, 100x100mm, thickness 2.0mm, as rolled, 99.95%
钨, foil, 150x150mm, thickness 0.125mm, as rolled, 99.95%
钨, foil, 150x150mm, thickness 0.15mm, as rolled, 99.95%