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  • Tungsten, the surprisingly positively acting heavy metal element for prokaryotes.

Tungsten, the surprisingly positively acting heavy metal element for prokaryotes.

Annals of the New York Academy of Sciences (2007-12-22)
Jan R Andreesen, Kathrin Makdessi
ABSTRACT

The history and changing function of tungsten as the heaviest element in biological systems is given. It starts from an inhibitory element/anion, especially for the iron molybdenum-cofactor (FeMoCo)-containing enzyme nitrogenase involved in dinitrogen fixation, as well as for the many "metal binding pterin" (MPT)-, also known as tricyclic pyranopterin- containing classic molybdoenzymes, such as the sulfite oxidase and the xanthine dehydrogenase family of enzymes. They are generally involved in the transformation of a variety of carbon-, nitrogen- and sulfur-containing compounds. But tungstate can serve as a potential positively acting element for some enzymes of the dimethyl sulfoxide (DMSO) reductase family, especially for CO(2)-reducing formate dehydrogenases (FDHs), formylmethanofuran dehydrogenases and acetylene hydratase (catalyzing only an addition of water, but no redox reaction). Tungsten even becomes an essential element for nearly all enzymes of the aldehyde oxidoreductase (AOR) family. Due to the close chemical and physical similarities between molybdate and tungstate, the latter was thought to be only unselectively cotransported or cometabolized with other tetrahedral anions, such as molybdate and also sulfate. However, it has now become clear that it can also be very selectively transported compared to molybdate into some prokaryotic cells by two very selective ABC-type of transporters that contain a binding protein TupA or WtpA. Both proteins exhibit an extremely high affinity for tungstate (K(D) < 1 nM) and can even discriminate between tungstate and molybdate. By that process, tungsten finally becomes selectively incorporated into the few enzymes noted above.

MATERIALS
Product Number
Brand
Product Description

Tungsten, foil, 0.2m coil, thickness 0.05mm, coil width .51mm, as rolled, 99.95%
Tungsten, foil, 0.2m coil, thickness 0.02mm, coil width .1mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.016mm, coil width .36mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.1mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.05mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.08mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 0.2m coil, thickness 0.10mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.035mm, coil width .75mm, as rolled, 99.95%
Tungsten, foil, 0.2m coil, thickness 0.1mm, coil width .6mm, as rolled, 99.95%
Tungsten, foil, 1m coil, thickness 0.1mm, coil width .6mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.035mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 1m coil, thickness 0.025mm, coil width 1mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.08mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 1m coil, thickness 0.08mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.1mm, coil width .6mm, as rolled, 99.95%
Tungsten, foil, 0.2m coil, thickness 0.1mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.6mm, coil width 1mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.02mm, coil width .1mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.035mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 2m coil, thickness 0.10mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.1mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.04mm, coil width 0.7mm, as rolled, 99.95%
Tungsten, foil, 5m coil, thickness 0.10mm, coil width .9mm, as rolled, 99.95%
Tungsten, foil, 1m coil, thickness 0.035mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, foil, 0.5m coil, thickness 0.6mm, coil width 1mm, as rolled, 99.95%
Tungsten, foil, 5m coil, thickness 0.1mm, coil width 1.5mm, as rolled, 99.95%
Tungsten, mesh, 50x50mm, nominal aperture 0.2mm, wire diameter 0.05mm, 100 wires/inch, open area 64%, plain weave mesh, 99.95%
Tungsten, insulated wire, 20m, conductor diameter 0.075mm, insulation thickness 0.02mm, PTFE (polytetrafluoroethylene) insulation, 99.9%
Tungsten, foil, not light tested, 50x50mm, thickness 0.005mm, 99.95%
Tungsten, insulated wire, 0.5m, conductor diameter 0.015mm, insulation thickness 0.002mm, polyimide insulation, 99.9%