Molybdenum and tungsten oxygen transferases--and functional diversity within a common active site motif.
Molybdenum and tungsten are the only second and third-row transition elements with a known function in living organisms. The molybdenum and tungsten enzymes show common structural features, with the metal being bound by a pyranopterin-dithiolene cofactor called molybdopterin. They catalyze a variety of oxygen transferase reactions coupled with two-electron redox chemistry in which the metal cycles between the +6 and +4 oxidation states usually with water, either product or substrate, providing the oxygen. The functional roles filled by the molybdenum and tungsten enzymes are diverse; for example, they play essential roles in microbial respiration, in the uptake of nitrogen in green plants, and in human health. Together, the enzymes form a superfamily which is among the most prevalent known, being found in all kingdoms of life. This review discusses what is known of the active site structures and the mechanisms, together with some recent insights into the evolution of these important enzyme systems.
Molecular and Environmental Science Research Group, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada. g.george@usask.ca.
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Julien J
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Graham N
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George
D001665:Binding Sites; D020134:Catalytic Domain; D003067:Coenzymes / Q000737:chemistry* / Q000378:metabolism; D008667:Metalloproteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry* / Q000378:metabolism; D000090006:Molybdenum Cofactors; D010100:Oxygen / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011621:Pteridines / Q000737:chemistry* / Q000378:metabolism; D014166:Transferases / Q000737:chemistry* / Q000378:metabolism; D014414:Tungsten / Q000737:chemistry* / Q000378:metabolism
D003067:Coenzymes; D008667:Metalloproteins; D008982:Molybdenum; D000090006:Molybdenum Cofactors; D010100:Oxygen; D011621:Pteridines; D014166:Transferases; D014414:Tungsten; C022261:molybdopterin