Molybdenum and tungsten-containing enzymes: an overview

Maia LB, Moura I, Moura JJG. "Molybdenum and tungsten-containing enzymes: an overview." In: Hille R, Schulzke C, Kirk M, eds. Molybdenum and Tungsten Enzymes: Biochemistry, RSC Metallobiology Series No. 5 (ISBN: 978-1-78262-089-1). Vol. 28. The Royal Society of Chemistry; 2017:.


Molybdenum is essential to most organisms, being found in the active site of enzymes that catalyze redox reactions involving carbon, nitrogen and sulfur atoms of key metabolites. Some of the molybdenum-dependent reactions constitute key steps in the global biogeochemical cycles of carbon, nitrogen and sulfur, with particular emphasis on the atmospheric dinitrogen fixation into ammonium. Presently, more than 50 molybdoenzymes are known. The great majority are prokaryotic, with eukaryotes holding only a restricted number of molybdoenzymes. Tungsten, probably because of its limited bioavailability, is less used, being found most often in anaerobic thermophilic prokaryotes.

This chapter provides an overview on the molybdo- and tungstoenzymes.
Their physiological context and significance will be described in Section 1.2,where the recent hypothesis that the lack of molybdenum could have been the limiting factor for the life evolution and expansion on early Earth will receive special attention (Section 1.2.1). A brief introduction to the chemical properties that shape the catalytically competent molybdenum/tungsten centres will be made in Section 1.3. In Section 1.4, the enzymes will be grouped in five main families (Sections 1.4.1 to 1.4.5), according to their metal/cofactor structure, and a general view on the structural (section (a)) and mechanistic (section (b)) versatility of each family will be presented. A brief account of novel heteronuclear centres containing molybdenum, whose physiological function is not yet fully understood, will be made in Section 1.4.6. A final outlook on our present knowledge about these enzymes will conclude this chapter.

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