Molybdenum biologically active chelates

Iron is transported in forms in which it is tightly complexed to small chelators called siderophores (microorganisms) or to proteins called transferrins (animals) or to citrate or mugeneic acid (plants). The problem of how the iron is released in a controlled fashion is largely unresolved. The process of mineral formation, called biomineralization, is a subject of active investigation. Vanadium and molybdenum are transported as stable anions. Zinc and copper appear to be transported loosely associated with peptides or proteins (plants) and possibly mugeneic acid in plants. Much remains to be learned about the biological transport of nonferrous metal ions. 

The molybdenum cofactor (Moco) is an extraordinary molecule in biology. As a small metal-containing compound, it has the unprecedented combination of a dithiolene chelate for metal binding and a pterin appended to a pyran ring. The resultant cofactor is electronically nimble due to the presence of three redox active moieties, ie. the molybdenum atom, the dithiolene and the pterin, which in concert can support a range of redox events. 

A further application of TLRC in the biochemical field is in the assessment of the activity of enzymes, where TLRC can be used to monitor and quantitate the products during the course of an enzyme reaction such as deiodination. Other examples of the use of TLRC in biochemical studies are the qualitative assessment of the complex-forming ability of metals and ligands in biological systems and the complex formation of heavy metal chelates, such as molybdenum species with poly-aminocarboxylic acids. 

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