Tungsten biology

Tungstates, decachlorooxydi-, 3, 990 Tungstates, nonahalodi-, 3, 999 Tungstates, thio-. 3, 982 Tungstate X, 3,1034 Tungsten biology, 6, 667... 

It appears that chromium(III) is an essential trace element in mammalian metabolism and, together with insulin, is responsible for the clearance of glucose from the blood-stream. Tungsten too has been found to have a role in some enzymes converting CO2 into formic acid but, from the point of view of biological activity, the focus of interest in this group is unquestionably on molybdenum. 

Hille R (2002) Molybdenum and tungsten in biology. Trends in Biochem Sci 27 360-367. 

Kroneck PMH, Aht DJ (2002) Molybdenum in nitrate reductase and nitrite oxidoreductase. In Molybdenum and Tungsten- Their Roles in Biological Processes. Sigel A, Sigel H (eds) Marcel Dekker, Inc., New York, 369-403... 

The electrosynthesis of hydride complexes directly from molecular hydrogen at atmospheric pressure by reduction of Mo(II) and W(II) tertiary phosphine precursors in moderate yield has been described as also the electrosynthesis of trihydride complexes of these metals by reduction of M(IV) dihydride precursors [101,102]. Hydrogen evolution at the active site of molybdenum nitrogenases [103] is intimately linked with biological nitrogen fixation and the electrochemistry of certain well-defined mononuclear molybdenum and tungsten hydrido species has been discussed in this context [104,105]. 

Vanadium and chromium have been shown to be essential by nutritional studies. Of the remaining metals, it appears possible that tin and tungsten may be essential. The biological properties of the essential metalloids such as selenium1035 and arsenic1060 will not be considered. 

I. INTRODUCTION THE MOLYBDENUM AND TUNGSTEN ENZYMES, A BIOLOGICAL PERSPECTIVE... 

There were 37 distinct enzymes that contain molybdenum or tungsten known by the end of 1997. The enzymes are diverse in function, broadly distributed, and include oxidases, reductases, dehydrogenases, a transhydroxylase, and a hydratase. The Mo enzymes are found in eubacteria, archae, protista, fungi, plants, and animals (including humans) and are essential for respiration and carbon and nitrogen assimilation. Several of the enzymatic substrates and products are key components in the nitrogen, sulfur, selenium, carbon, and arsenic cycles and have major biological and environmental impact. 

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